I'm using basically the same thing. Except a hollister single piece pouch system. I'm also using a skin barrier product from 3M called cavilon which is a miracle product. My wife has had Ostomy problems for years and just started using it and it extended her wear time from 2 to 5-7 days. If you want, I can send you a few packets.
One more thing that helped was a convexity in my pouch. I have a chubby middle so it helped to have a solid form there.
BTW, my Ostomy is the only thing working. I'm back on FOLFOX chemo and feeling like total XXX. Only 7 more weeks to go.