There was a post several years ago here that described small animal heating pads that could be set to a desired temperature. The example shown was for baby piglets. It might be of interest here.
I prefer to do things at room temp.
Regarding C-41, current Bleach III consists of 2 parts. Versions from 3 or 4 years ago used 1 part. Replenisher for bleach, fix and stabilizer are not needed.