I've been busy doing some upgrades on my 2018 321RSTS. Here's a few that I've done and some results and opinions.
Installed Lippert Solid Step stairs:
https://www.etrailer.com/RV_and_Camp.../LC678027.html
This was a very easy and straight forward installation. I removed the original steps first and modified the threshold as instructed. I did watch a YouTube video on installing the stairs and it was right on. The stairs are very solid and well made. IMO they are much better than the original fold out stairs that flexed each time we used them. No flex on the Solid Step stairs. (I am working on getting some LED step lights to install on the stairs. I'll report on that project later when I get it done.)
Installed Lippert Storage box where old stairs were stowed:
https://www.etrailer.com/RV_Cargo/Li.../LC664640.html
Although this is expensive for what you get, it does add an element of additional storage in an un-used space. The storage box comes with no instructions but it's not a difficult installation. I painted the box to match the trailer apron a little better than the flat black. The box is well built and easy to install.
MaxxFan vent fan:
https://www.etrailer.com/RV_Vents_an...00-07500K.html
We only have one operational vent in the 321RSTS. It's in the bathroom and the stock vent is loud and very difficult for my wife to reach the switch. I decided on the remote controlled vent fan from MaxxFan. It's a 10" fan with 10 speeds and remote opening feature. This is an awesome upgrade. Now my wife can operate the fan easily and it is much quieter than the stock fan. Installation was pretty straight forward but the screws that came with the fan were too short for my installation. I solved that easily. I also found the interior vent shroud that came with the unit to be too short for our roof. I did a little trimming on the original shroud and it fit fine. I used the self leveling sealant to seal around the fan opening and I like the way it worked.
https://www.etrailer.com/RV_Exterior...7034145-1.html
Sewer Hose Carrier:
https://www.etrailer.com/RV_Sewer/Va...04-5094BK.html
This was installed under the rig on the trailer frame. This item stretches to fit the outside frame rails. I did add a small spacer on the driver's side of the fiver to allow some room for an LPG hose. This carrier is built well and was pretty easy to install. I can easily fit 3 sections of sewer hose in this carrier so it's now out of my storage unit and under the RV where it can't cause any problems.
Interior lights:
https://www.etrailer.com/RV_Lighting...77-000334.html
I've installed 4 of these lights over our recliners and sofa to replace the little, flat LED stock lights. Now we have directional lights that are much brighter and make reading easier. These lights have individual switches and are directional so we can use them independently or together.
I'm doing some more upgrades but these are a few of the more important ones that will make the RV more user friendly. We'll be making some longer trips this year so we want this unit to be as comfortable as possible. Use YouTube whenever possible to get an insight on whatever you're doing to your RV. Getting a head start and knowing what problems others have run into will make your experience run smoother.
I got all of my parts from Etrailer. Great service and products there. I've had very good experienced with Etrailer.
Enjoy you Jayco...