Hi John,
I don't want to come across as preachy but there are a few measures that can be done for constipation.
I've found the following helped me a lot in overcoming this problem.
I was a registered nurse before my change to a parkinsonian and so have seen my fair share of bums!
Flavour a jug of water with some lemon and or lime to make it more palatable and make sure you drink it all by say lunchtime.
Then do same in afternoon. I try and change to something like green or peppermint tea in between.
Increase your fibre intake.
Grainy type bread, more veggies, fruit.
I find apples are particularly helpful. Lots of different fresh fruit and nuts to snack on helps.
You're at a high risk of a prolapse with all that effort plus taking fluids orally is much more fun than rectally!
Good luck!