As long as you can build up the hull
structure to spread out the loads better should be doable. Guessing G10 fiberglass
board from McMaster Carr would be best. What about getting to the vberth/head? What about keel
bolt access and limber holes? I haven't looked at mine in this context as the cross beam is solid in mine. Bear in mind that the top of the compression
post must be solidly located anyhow, otherwise sail forces could push it sideways, crushing a weak cabin
top skin /structure.