I think I'd like to keep my knees...do you think there would be a way to almost "re invent the wheel" and make a split capable of skiing and riding normally?
I don't see how. If you had a sidecut on the inside edge, it would ride all kinds of fucked up. The binding issue would be pretty tough too.
I don't see why you'd want such a thing to be honest. Buy skis for skiing and boards for riding. Splitboards only split for the hike up. There's no intention for them to be used as skis on the downhill.