Hunting around the internet for Econoline swivel seat bases, I found my way to this thread. A lot of planning and work went into this project, and it shows. The thing looks great!
It's a pretty long thread to shift through, but discovering the existence of a Rivet-Nut tool, and the 8020 railing system alone was worth sorting through it. Especially the Rivet-Nut tool. That is a perfect, and elegant solution to building out or customizing vehicles.
With respect to interior lighting, you were considering installing recessed LED lamps. It's too late for this now because those cabinets look great, but an alternative for future builders considering a similar path, would be to use a translucent privacy screen similar to what's in this picture:
The advantage of going this route is it would probably make the interior feel more spacious, but also those LED strings could be installed inside of the cabinets as the general house lights. I've got a string in my cargo van, and let me tell you, they are VERY bright.
Anyways, like I said, great job on this project. I, like many I'm sure, am curious to know the final tally for all the modifications.