I just had a brainstorm and wanted to share an idea with anyone else who might need to conserve as much space as possible.
I have been thinking of a good place for my garbage can. Under the sink cabinet seems an ideal place, but I won't have a lot of cabinet space to begin with, and I'd rather not have the possibility of garbage sharing a location with pots and pans. Keeping the can in the open means I'll have to deal with the smell and two curious dogs who may decide to tear into it when I'm not around. I had even toyed with the idea of a chute through the floor into a can mounted to the frame rails, but then emptying the trash in anything other than perfect weather becomes a nightmare and it's not exactly "bear-safe."
This is what I came up with: I had previously designed a door for the shower enclosure that would double as storage for odds and ends. This door isn't the primary means of keeping water in the shower stall—there is a typical shower curtain for that. Instead, it merely hides the shower and keeps a neat appearance. Well, into this door I can also put a tilting trash can holder that can be accessed from either side of the door. I can open it from the outside when the door is closed, or tilt it inward while the door is open so I can access it while the rear of the vehicle is closed off (if I have a guest and I want the dogs separated, this is how I'd do it).
(Some of the details still aren't to exactly the correct scale, but you get the idea.)