I still think the longer segment is the way to go but after talking with Menscer's tech they've convinced me they can make the 20" work. I even gave them the option of the longer spring and they said it's not needed. Since I already own the shocks its just the cost of the valving. I'm looking at the same money to relocate and (re)buy the parts for the springs.

I still plan on mounting the shocks straight up, and maybe move them to the front of the axle.

For the OP - I'd still go with the longer springs. I haven't heard anyone report regretting doing so.