Well, I guess I am well past the prototyping stage now but I'll just add to this post to keep the story going.
I built out the side counter cabinets and side dinette and we took several trips this summer. It worked great, but now I'm tweaking things a bit and it is a good time to catch up the post.
Here are the side cabinets with no shelves or counters. I used 1/2" Baltic Birch with a water based lacquer-type finish. I used a frame construction to reduce weight.
The counter cabinet is 16" wide. The same width as the wheel well inset. That is a little narrow, but we like having some room to move around in the camper. I fastened a partial bottom under the frame side panel so it is flush with the upper inset of the floor pack. To keep things in the bottom of the cabinet, I hinged a 3" flip-down lip with spring roller catches.
Below the cabinet I have a stretch net to create a little storage for towels and what-not.
The cabinets are drilled with shelf pin holes for shelves. I want to keep things adjustable. I found some locking shelf pins to keep the shelves in place.
The shelves are a frame construction with 1/8" oak plywood centers. Nice and lightweight. I had scraps of the oak plywood left over from another project. Otherwise I would opt for something less expensive. But it makes a nice looking shelf.
The shelves also have the hinged lip, but I attached an angle brace to the shelf to hold the spring catch. That way I can move the shelf where I want it without screwing the catch into the cabinet panel.
Cabinet with empty shelves.
I found these really inexpensive plastic bins at Bimart that are just about the right size. And very lightweight. There is a short and a tall size.
I can get four short bins or two tall bins in a cabinet.
With the lip down, it supports the bin when it slides out. They come out far enough for access. Not quite as smooth as drawers with drawer slides, but a whole lot lighter and more adjustable.
That is enough on the side cabinet for now. Time to go to bed. I'll work on getting pictures posted of the counter and side dinette.