On the question of how much solution, I suspect that I'm envisioning using more than most folks are used to using on platter machines. I'm thinking of putting the fluid in a trough and running the record through it with some sort of brush mechanism in there too. Then a second and probably third trough for rinsing. In a crude way, its not unlike a bar that uses three sinks in succession to wash glasses. Yes, you would ultimately have contaminants in the soap solution, but if youre rinsing well and then vacuuming dry, how much could be left over on the playing surface (a loaded question, Im sure)?
I actually think the troughs will be easy. As a prototype, just to test the cleaning part, I can even use three tubs. They dont have to be connected or anything. Finding the correct brush will be a bit of a challenge, and of course the vacuum system.