I went and bought a big bag of "depends" before my RP, but guess what? It turned out that wasn't my problem. Now that's the kind of problem I prefer :-).
Just saying, we don't know what our personal situation will turn out to be like. And as we all know, we can't trade problems with each other--and my guess is that probably wouldn't work out well anyway.
After the catheter came out, I used a scale to weigh the diapers to figure out how much I was leaking.