OK!
I decided next will be the Coopers Stout, so I am spending the early part of the day cleaning the carboy.
Something I tried:
I use almost exclusively the Grolsch bottles. When I was at the brew store yesterday, I picked up some new washers, but was somewhat displeased, they seem substandard.
So I removed all the washers from my current bottles. The biggest enemy of rubber is drying out and cracking. So I put them in a cup, and put in about 3 tbsp of olive oil.
Checked (and washed them off) this morning. The dents caused by the bottles being closed are almost gone. They are much firmer and more pliable than the unoiled equivalents.
So y’all might want to try this!