I did the very thing on a pair of pace forks I had (kind of wish I still had them) and to be honest it worked quite well. I can't recall what I used in the middle of them but it was about the sane as with full elastomers, not the pogo that people talk about with undamped springs as the elastomers do half the work. Hell, older Judy forks were part spring, part elastomer but then they did have damping (of sorts).