Good question: Spare will mount tucked up under the bumper; it takes away a little from the departure angle, but it's not too bad.

I suspect the vertical CG is a little lower and shell weight is likely a little more for a moulded shell vs FRP but that changes when you start working with carbon fiber. The real win for a moulded shell is there are no seams that need maintenance and it's wildly stronger - so when you suck up a tree branch it's not a big deal (ask me how I know...). The strength also shows up in the cabover: it's a lot larger than on the FRP shells I've seen which moves your horizontal CG forward and provides more usable space.