First, Howdy and Welcome to Irv2.com
A few things you need to watch would be what is the max tow rating of your truck, since you say your going to tow another trailer also? And a few things to consider for the trailer along with what can you tow, is What you need. How many dose it need to sleep, Will you need heat or air conditioning, and what type of camping will you do? (boondocking or hook ups) Let us know.
Something I have always advised is find a RV show close by where several different manufactures will be present for a real look and know what you want so you can see what you will need the find the price range you need.
Good luck, take your time and find what you want.