These are the two designs I’m considering for MegaRail Z. They’re up on GitHub, also as PDF here and here.

The right side is the same in both cases.  The only difference is that the first profile has an additional T-slot. The side T-slot can be useful for attaching shields (in certain configurations), tabs for limit switches, and other accessories like that. The larger footprint is a disadvantage.

Both profiles have exactly 15 mm between the V centerline and the base. With standard MakerSlide V-wheels, this gives 21.45 mm of space between the carriage and the surface MegaRail Z is attached to. That should be enough for smaller lead nuts (a Tr 8 anti-backlash nut is typically 20 mm diameter).

I sent all variants I’m considering out for costing, and I’m hoping to hear back from the extruder soon.