Hmmm....I have never heard of these before? What about just buying him some disposable diapers?
Is the reason you wanted disposable ones because he sometimes marks on the actual belly band itself (by accident I mean) and it is a pain when you are traveling?
If so, one thing that might help is to get bigger panty liners. You can actually buy the bigger/wider/longer PADS that women use....they allow for more coverage on the sides of the belly band, and in the length as well.
I hope this helps hun