My suggestion is to keep the towing weight down to 7K or so. Look for a trailer that starts out 5K or so, and you'll end up towing a little over 6K and your truck will be very happy! My Tundra is technically rated for 10K, but I'm towing 6.5K or less and it's a great match, even with 2 folding bikes, blue tote, tool box, etc. in bed of truck. There's just DW & me in the truck. And, we had our rig out in the Rocky Mountains last year and it did very well.
Consider looking at the Winnebago Minnie line. I follow a couple of forums, and most owners have been very pleased with them. We've had ours since the fall of 2013 and it's been a good trailer. Grand Design also has some interesting trailers, with 4 season features but they are a bit heavier and cost more.