I can't place traps there, but I walk by regularly. When do they drop? How do I collect the galls or wasps in a form that will keep them alive? I'd send them to you rather than try to store them in outdoor conditions.

The galls are "ripe" by September--reddish and speckled like this:

and easily detached. If they come off easily then it's safe to remove them, and just put them in a plastic vial or something similar. I've found a few on the ground too, but that's obviously more difficult. Collect as many as you can--I only had wasps emerge from a small percentage, although there's some chance that more will emerge in another year or two... I'd be happy to have any you can find. I don't have many oaks near my house, so I'm less likely to find these now.