Your best bet is to put your wallet in your carryon and then close it with a zip-tie. Demand to keep your bags in your sight at all times. If you need a patdown, ask the screener to retrieve your bags before they do the patdown. If they want to inspect your bags, the zip-ties will (hopefully) keep them from opening them until after your screening is done.

I carry zip-ties and some small nail clippers in an unlocked outside pocket of one of my carryons. I use the clippers to remove the zip-ties.