Well, among other things, I am interested in recumbents as well. The problem there is that recumbent geometry isn't as pat as on diamond frames. There's a lot more variation, not just the same old 71-73 degree head angle with stock rake. So to properly dial in steering with any given head angle if you're not riding a production recumbent, you'd need either a few different forks or one adjustable fork. Ideally, adjustable head angle would also be on the table, but that's very difficult. Even Angleset only gives you a couple of degrees variation, whereas recumbents can go as slack as 45 degrees (and require several inches of rake), a big difference from the 70s. Maybe if there was some kind of pivot on the head tube like on a swing arm. I suppose the front end is no more highly stressed than the rear end of a full suspension mountain bike, but roll stiffness would be much more critical at the head tube joint.
As for your multiple dropout positions, that would require readjustment of v-brakes every time you changed position, otherwise you risk cutting the tire sidewalls or pads falling into the spokes. Disc brake readjustment would be impossible, unless you made the disc tab also movable to any of four positions.