Where to start.
ProLine. My buddy bought one of their 24' enclosed trailers a couple of years ago. Over a few months of normal use (well within gvw, but a lot of miles) the frame developed a bow. As time went by you could just look at the thing from the side and see it getting more bent over time, and gaps began to develop at floors, walls, trim. Took him months of everything but a lawsuit to get them to take it back. They gave him a new one which he promptly sold and bought a different brand.
Excursion. Don't even consider a trailer with less than 14k gvw, 8 lug axles, 16" tires. Even with a light weight open trailer you will pretty much be maxed out as soon as you drive the empty truck on there. And trust me, from putting 100's of thousands of miles on enclosed trailer and changing many many tires and a few sets of axles, you don't want to be right at gvw. The tires and axles will not hold up under extended use. You want to be overspec on the axles/tires. Picture it this way as the weight is the same, you wouldn't even consider driving your excursion with weenie 15" tires with the weight of a trailer stacked on the roof.
Stackers. You can certainly get any option you want in a stacker. It's kind of like the old racing adage: "speed costs, how fast do you want to go?". Becker makes some nice units:
22' PLUS 4' APACHE ALUMINUM STACKER | Becker Custom Trailers
That one is a 22'+4' configuration to keep the length down and storage up. As to the teenagers, get 'em some air mattresses, they're young and tough and will be happy to have their own "room". Looks like room for a car, bikes, and a golf cart in front. plus tons of cabinets.
What about a mini/split a/c unit? The out side unit could go on the front instead of the top that way.