MrScary: I've had a porta bote for over 3 years now and we really like it!
We have a 26 ft Starcraft 235fb travel trailer and my wife and I like to fish, but we always had to fish from shore. But with the porta bote, we can get out on the water wherever we go camping.
We bought a 12 footer, which is a good size. I can handle it myself if I have to (the folded up hull is about 75 lbs), but usually the wife also helps. The 14 footer would be too big and heavy for me alone. Since your TT is only 20 ft, you may want to go for a 10 ft boat. That big window on the driver's side of the TT may be tough to work around. Some people mount the PB under the trailer, if you've got enough road clearance. Or you can just strap it to the top of your van, that would be the easiest thing to do.
I have a large duffel in which I keep the seats, transom (newer porta botes have a folding transom that stays in the hull) and a 40 lb thrust trolling motor. It literally takes only about 10 minutes to put together once you get the knack of it.
The floor of the boat is a little squishy, but you get used to that and can even stand up in it to fish. Join the Yahoo group porta bote forum to find lots of mods that people have done to their botes. I've added a bow-rigged anchor hanger and some rod holders.
You might hear a lot of criticism of portabote, but it nearly always comes from people who've never been in one. I don't know any PB owners who don't like their bote.
I mounted mine to the side of my TT. Here is my post from a few years ago that shows exactly how I did it. http://www.jaycoowners.com/forums/f1...iler-7457.html