My family has a 2006 Jayco 29 FBS TT. We bought it at 1.5 years old. And, we've been loving it ever since. And where needed, we upgrade it with "better then factory" fixes. For example, under added belly spray faom, installed "hard wired" Surge Guard, installed 2 x MaxAir roof vents (1 x black and 1 x white - over the bathroom), installed a battery switch, installed rear fridge fan, installed much better brake wiring, re-sealed its 11 windows, etc. etc.
We bought this specific floor plan because of its bathroom layout. As seen in its floor plan layout, the toliet / sink is on one side of the hall. And, the shower / tub is on the other side of the hall. Our son is physically disabled and needs help in the tub / shower. And to keep his body healthier, he aways showers after swimming. While helping, we are "in the hallway" - with lots of room to help. In "single room" bathroom layouts, the person helping (the other person in the tub) has their face in the toliet. Or, the toliet (in the same small bathroom) is in the way to assist them in/out of the tub. For helping a disabled kid or other persons, the split bathroom is a great idea. For safety and "ease of help", split bathrooms are a must have....
On a positive side benefit of "split bathroom" is its "end / end line of sight" layout.. For example, its hallway and its door is now in the middle of the trailer. My wife (laying on the left side of the master bedroom bed) can easily see all the way down to the opposite end of the trailer. She can see our kids getting out of bed in the morning or watch "with one eye open", who is making themselves breakfast. If our disabled son tries to make breakfast, we have to immediately assist. With traditional bedroom wall (and doors on far side of the wall), one needs to keep getting out of bed - to peak around an off-set bedroom door way. Now, she can lay on the left side of the master bed, read a book (or sleep in) and still keep a clear view on things. Ther person on the right side of the bed cannot see down the trailer. Thus, the right side of the bedroom has more visual privacy for this person. And, allows a little privacy area to change one's clothes in the master bedroom as well.
The power vent above the kids sleeping area lets in too much light. Last summer, we installed a Maxair (actually, MaxMate - different vent company) and we purposely picked Black color. Thus, blocking more light in the rear bedroom area. I also tinted (dark limo) the larger (lower) bed winder as well. Thus, creating a darker area - for kids to sleep in longer. The closet across the rear bunks is great. If kids are small, I'd recommend a safety rail on its upper bund. When kids were small, I created my own safety rail from steel pipes and painted them brown. Clean and simple.
The lower rear bunk can support a heavy short person. If worried about over weight (on the bottom bunk), simply open its under side storage compartment and install some 2x4s - to create vertical supports. The upper bunk won't hold very much body weight. Max 150 lbs sounds about right. The upper bunk is good little kids but not for a heavy adult. Do keep in mind these rear bunks are short. They are made for kids - not tall adults.
If I remember correctly, Jayco made the FBS models until early 2009. (last build in late 2008). The newer models have the same floor layout. Except the kitchen counter top end area comes out (creating more counter space) and their TV/DVD Entertainment area has different cupboards (actually, newer years have flat TV counter top instead of factory shelfs). And its "under the slide" area above the sofa has some little storage cupboards as well.
With large TTs (like the 29FBS), most people "load heavy". Its like one of those, "larger garage = more stuff one has" things in life. Therefore, do view your loaded 29FBS trailer behing near its max loaded weight. Especially if you have kids and they need lots of stuff as well.
For water tanks size, not too sure. We have our TT at a seasonal site and the CG staff empty our tanks every Tuesday AM (or Thursday - if Tuesday is rain day). Thus, we don't over fill our tanks.
We've opened every window on our TT except its front window. With front window open, I get a cold / draft feeling. Especially when trying to sleep. Thus, we keep its front window always shut. I do wish its bed was longer (for my 5'-11" body). When its current factory mastress is worn out, I want to replace with a "normal size" Queen bed. Something that is 12" longer. Would loose the "walk around" ability at the foot of our bed. But, with longer matress, I could sleep with my feet under covers - instead of them always sticking out the end of the short bed. On a positive note, the bedroom area layout does allow for a longer matress.
As a minimum, I would recommend removing its 11 windows (yes, simple DIY task over 3-4 weeks), remove their factory rubber gasket and replace this dry rubber seal with soft putty. Thus, sealing the windows properly - the "old school" way. Dry fit windows (that Jayco loves to use) don't work in the long run. Especially on older age trailers. Of the 11 windows on my 2006 Jayco 29 FBS, 3 of them were leaking water. And, one was leaking really bad "inside" the wall. And, I didn't even notice it. For cool video on how to re-seal TT windows, surf:
Due to its large flat slide roof and older age (when floot roofs that pool water start to leak), I'd recommend mandatory slide cover for your 2005 Jayco. If you plan to tow this trailer, get the spring loaded soft awning slide topper. If you plan to park your large TT at a seasonal site (like my family), I'd recommend a custom made "hard top" slide cover. Hard covers can be mounted with more roof slope - which is better in the long run. Regardless if soft or hard, IMO, a slide topper over the slide's flat roof is mandatory. If wondering, I plan to install my slide's custom created "hard top" slide cover in 3 more weeks.
Would I buy the 29FBS model again? Yes I would. Especially because of the many benefits of its split bathroom layout and its "clear line of sight" from the master bedroom bed to the opposite end of the trailer. Clear line of sight is great - especially when one needs to keep "one eye on the kids" while laying in your master bed (enjoying your own space) and reading a good book.
Hope these items help in your FBS research....