There is a lot of good information here, but I agree with those who suggest who seek out every resource you can to learn as much as you can. Even go visit an RV park and find some folks who don't mind telling you (and showing you) the differences. RV'rs are a friendly bunch who will likely be happy to help you out.
One thing I didn't see mentioned was deciding what works for you. TT and 5ths are different in many ways, similar in others. I agree with those who say a properly setup TT tows fine, but what I am leading to is this: Find the floorplan and accessories and all that stuff that works for you, and perhaps let that be the deciding factor. Things like whether you can access the bathroom, kitchen, bedroom with slideouts pulled in. On mine, I can, so for a night at a Walmart (or wherever that I don't unhook) I stay hitched and can get to everything I need. Whether or not stairs will be an issue. Enough storage? All those types of things. You might end up with a TT, or you might end up with a 5th depending on which one has everything you want.
The old saying "buy your third rig first" IMHO speaks to a lot. That means lots of research initially.
Same thing with a truck. If you have a 1500 now and you buy a TT, fine, but if you want to do a large upgrade, then you need a new truck.
Just my 3 cents. Good luck with it all.
Edit: Typos
