Having already faired the bulkheads for my "Flying Cloud" and plan to use balsa blocks between, I fear I'm a little late like Spring with this same question. But I too would like to know what you recommend for future reference. I faired the bulkheads first because I could do it off the model. But I guess that would be less of a problem once the balsa blocks are glued in between. Following your builds is very instructive generally, as well as to any specific model you happen to be building.
I look forward to following along.
Pete