Lots of great ideas on those sites Bogo and Bob. My problem is that as a full-timer I need to get rid of stuff so I don't have to try and cram it all into the Caboose, not so much finding new ways to make more space so I CAN cram it in!
There's also the whole weight issue, less is better.
At the same time, there are some things I will not skimp on... I prefer to use real dishes and silverware, not paper or plastic. In fact, I plan to take a couple place settings of the fancy (Lenox?) china my grandparents got for their 50th wedding anniversary. If I break it I will have some more at home to replace it with, until it's all gone. It's not a complete set now, and none of my kids expressed any interest in it, so what the heck, it's beautiful and I'm going to use it. Same with glasses. And of course my cast iron.
I love to read, so I'll probably try and incorporate a book shelf somewhere so I can cart some of my favorites along with me. I'm a motorcyclist, and plan to take the bike on the back porch of the caboose, so the bulky boots, helmet, jacket and pants along with my tankbag need a space. I currently have 3 dogs: a yorkie, a cocker spaniel and a great dane.
They're all quite old though, and I sadly don't expect the 2 bigger ones to be around by the time the caboose is ready to hit the road full time, but even the yorkie takes up space with food storage and his bed.
I spent the summer living in a 30' TT with a super slide, so I did learn a few things from that. There was tons of room to move around, the stereo was great, but I never used the back 6 feet of it - the jackknife sofa and the swivel rockers. If I was inside I mainly was at the table with my laptop or watching a little TV or reading. There were NOT enough cupboards for things, especially in the kitchen. There was a 2-door cupboard above the counter, but no shelves inside so it was just one tall open space. There were only 3 drawers, and another cupboard below the counter with space for a small trash can, pot and pan storage was a problem and they ended up in the overhead cupboards across the back above the swivel chairs. There wasn't a tall closet for things like a broom and coats, there were no drawers in the bedroom and the short narrow closets in the bedroom just didn't do anything for me. Neither did the cupboards above the bed that I had to climb onto the bed to access. The TV was mounted very high so I got a crick in my neck if I watched much in the evening. The bathroom layout was good, but no place for towel storage in the bathroom itself unless you crammed them under the sink with the TP.
Oh, and why don't they use real light switches on the wall near the door instead of making a person search for the switch on the light itself? There WILL be light switches inside the door of the caboose, at the entrance to the hallway leading to the bedroom, and at the bathroom door. Ahhhhh, the beauty of building it yourself.