There's a soname & sover change between OpenSSL 0.9.8 and OpenSSL 1.x, so I'm not terribly convinced nothing will blow up in strange and mysterious ways if you do.
(I'm not familiar with the details of OpenSSL's API/ABI [because it's hell], so this may be more feasible that I'm making it look).
I also don't know if the last 0.9.8 release, 0.9.8zh, is 'good enough' for what you hope to achieve.
What I can tell you is that I kept building my own stuff against 0.9.8 on those FWs to make my life easier and not have to deal with any of that kind of fallout

.