listen very carefully to what is being said above. Learn and understand all the weights associated with truck/trailer and stay safely below those max numbers. With your budget there is a lot of rigs you could buy...so go to a show, look at some of the ones that seem to fit your needs best then go home and do the math on those weights were all harping about!
Honestly rv's are such a personal choice that floor plan is in the eye of the beholder. Your asking a lot to sleep 6-8, separate master and tow with a Tundra, but I hope some folks here with similar needs will get you pointed in a good direction.
I say start with a few manufacturers websites and find some floorplans that look good