Hi Sue
I'm similar age to your husband, and at the same stage - contained PCa 3+4, and considering RP. Major difference being I don't have an enlarged prostate, no BPH and subsequent TURPs. The side-effects concern all of us and it's worth reading various threads on post op - some are dry very quickly post catheter removal, others struggling for much longer.
I haven't read anything that would indicate how you can stack the odds in your favour re: avoiding long term incontinence, but others will hopefully chime in. I did attend an afternoon session at the hospital do those considering / scheduled for RP, and the stats quoted were very encouraging - just note that the NHS view "Dry" as one day pad per day (from memory).
You have to have faith in your surgeon and make sure your husband is doing his PFEs - various apps to help him with those and keep track. Then stay positive.
As you probably already know, there is a wealth of information here from people who have gone through it, and it's a very supportive community.
Good luck.
Chris