Freeform: Options when running out of dimensions

Summary:

Freeform: running out of dimensions!

Content (please ensure you mask any confidential information):

A Freeform app I'm building as a POC has an ASO cube with Account, Period, and 24 (!) custom dimensions, the largest of which are currently 21K and 57K members, with another ten in single-digit thousands. It actually performs pretty well (other than editing dimensions, which is understandably slow.

We would like to also build a BSO cube, into which we can datamap certain of the ASO data, run some calcs to do some rate lookups, and then datamap it back, but we are, of course, running out of dimensions. I've come up with a number of options, but what do you think is the best path forward here?