Others will comment but I have 27' no slide jayco and only have a 1/2 ton 4.6 Tundra. While I'm not going up mountains regularly it does the job, so you should have a great TV (tow vehicle). For my 4p family the 27' is a great size. We don't spend lots of time inside, but if conditions force it we can all fit and kids can be in their bunk bed w/o them being spread all over everything in the kitchen converted bed as you get with smaller setups.
Bear in mind something I didn't know when I got my used trailer, the typical tires (ST) are only rated for 65mph.
Site reservations depends on when/where, just like when you are getting hotel. Beach camps, popular spots are tougher to get. By my limited experience in my area, sites are a mixed bag, some my combo barely fits in, others can hold a 35' rv towing a car and have room to spare. Good thing most places list space limitations.
This site has a great deal of info. Enjoy!
New to me 27BH towed by 4.6 Tundra