Nebraska, I understand your situation, but you know it's not sustainable for her not to toilet with your son. Sooner or later, that day will come. Even if you go with the PureWick, external catheters tend to slip, and bags will still need emptying. At some point, there will be an urgent BM.
So I think this is part of a broader discussion among the three of you. Remember your "we" statements, like "We want to take care of you the best way possible, and that includes Joe supporting Harry while Harry is at work, so we can give you, all the help you need, as soon as you need it..." It is also inescapable and can be mentioned that holding on to urine or stool due to scheduling makes it harder to continue to go naturally.
I wish I could say something more helpful.
Best,
Laurie