I am on my third toyhauler. The first was a 27 foot Weekend Warrior bumper pull, had that about three years. Moved up to a 35 foot Cyclone 5th wheel, had that about three years and was disappointed with the build quality of the unit and the attitude of the manufacturer (Heartland). Replaced the Cyclone with a Voltage 3200 in 2011. Still have that trailer. It has been towed over 30,000 miles. I have a 2015 GMC 3500 crew cab dually which replaced a 2003 Silvarado 2500 HD, both diesels. Given the requirements you described I don't think you will find a toyhauler shorter than 35 -36 feet long, and will probably need to look at 38 foot and longer 5th wheels. You will need a 1 ton truck, and probably a dually. Trailers are almost always heavier than the literature and the salespeople will tell you. I have found that putting toys in the garage will only reduce pin weight by 200 to 300 pounds, given the geometry of a 5th wheel toyhauler.
Make sure that the trailer has adequate tires, axles and brakes for the projected load and plan on spending a lot of time performing upkeep and maintenance.
Another factor to consider is how will you use the trailer, mostly in developed RV parks, or dry camping.