I bought a Haulmark 36' goose neck enclosed trailer. I did a basic finish out in the front half. Bed is up over the goose, cabinets in the front area and a cheap hardwood floor back to the fender wells. I can park our Jeep inside no prob, or fit our 2 RZR's inside. Wife has no prob camping inside but would like a window or two for some natural light. It has a roof top heat/AC unit, added a small water tank for a sink. We couldn't swing a full blown toy hauler and we didn't see many options for one that could fit a variety of different vehicles. This trailer was appx. $15k new last year and we have been very pleased with how it works out.
On several trips, we had some rain and we set up a large folding table and every ones camping chairs inside and were able to party in one area all together. I painted the floor with some light gray outdoor deck paint and sealed all my edges really well. After a trip I drag in the water hose and rinse/scrub out the floor and let it run out the back door.
When the trailer is not in use, we usually keep both RZR's inside. They stay clean and out of the way.