As much as some say identical hides are necessary I think that as long as they have two similar sized "cave" type hides u should be good, ditch the log, my ball has a manufactured cave on hot side, and I have a cereal box cut like a cave on the cool side, just double check your temps, I had been using the petsmart brand thermometers with probes and they showed right temps but until I bought a ir temp gun I didn't realized how off the temps could be some were not off much others by 5+ degrees double check!