Me, the wife, and four "boys"- ages 18 down to 9. That means there's always a couple of friends (usually female at this point!) along for the adventure. Most of our trips are within 6-8 hours of Park City, UT, usually not more than a week, but we do like to get off the beaten path as much as possible.
Years of experience of loading and unloading trailers, RVs, houseboats, etc. has influenced my design heavily. I want to spend my time on the trip, not getting ready for it or cleaning up. I've designed the rig to keep everything on-board that is always needed, while allowing for plenty of "non-permanent" storage space. So here's how the non-permanent (food, clothing, bedding, and activity specific gear) storage works:
1) Basement: Two 52"x24"x28" basement storage compartments with a 52"x52"x6" pass through space. This is reserved for non-permanent gear storage.
2) Roof Rack: The fold-down observation deck on the roof (had one on our previous rig and loved it) doubles as an 8'x10' gear rack for large items like kayaks, windsurfing boards, etc. It also protects the PV panel assembly during travel (the assembly is attached to the big rear slide so it moves back with it in camp-mode, exposing the roof deck).
3) Interior luggage: The "stair" assembly that give access to the cabover and roof hatch can hold 9 "roll-aboard" size luggage/gear bags. It will have movable dividers to allow different configurations, but it's a large storage unit.
4) Additional interior luggage: Since so many of our trips involve playing in the water, the shower doesn't get used very often, so it will have removable shelves so it can double as extra storage as needed.
5) Pantry: The galley cabinets have a lot of room for food, the refrigerator is a 10.5 cu.ft. model, and the dinette has six removable 22"x24"x11" crates for food and sundries.
6) Bedding: We're used to utilizing the cabover for blankents and sleeping bags, and it has it's own cabinets as well.
Plus-----The liftgate rack can hold over 800lbs of gear (two dirt bikes, an ATV, or a pile of mountain bikes, inflatable kayaks, etc.).
AND---- I'm building a matching 16', super-light trailer as part of this project. It has room for 8 dirt bikes, or piles of just about anything else. It also will have it's own toilet "closet" and wash basin. It's a modified V-nose design with a door on the front that mates up with the camper's rear door. It will also have toy-hauler style fold-down bunks on each side to accommodate 4 more bodies when needed. I'll put overhead gear racks (bus style have worked best in my previous trailers) along both walls for extra storage. If that's not enough, I can put more crap on the trailer roof! And if that's not enough, then I'm staying home.