I'm curious if you could build a leveling kit for your independent rings... I was imagining having a ~2.5 inch section of aluminum (you could use a lower grade of aluminum, as it wouldn't be a structural piece of the mount. This would help lower materials and milling costs, I suspect) roughly patterned after the center segment of your mounts. You could place the short piece of aluminum on top of the picatinny rail, and use the cut 10 degree slot much like you would your one piece mounts. Perhaps having a small lip on one side to index off of the side of the rail could ensure that the section is square and doesn't move during installation. Then, you could just remove the section after tightening the screws, leaving you with a level scope. In fact, this type of setup could be used on nearly any ring setup, so you could have a large customer base for such a product.
Is there enough room underneath a set of rings to do something along those lines?