You might try tack strips at the entrance to your hives. Carpet installers use them to hold down the edges of carpet. Skunks scratch at the front of the hive and then squash the bees that come out and eat them. The hardware store here carries it, complete with nails installed to hold it down.
The skunks do not seem to bother the hive on stands either. Their little undersides are subject to getting stung then, I believe.
Good luck!
Dennis Morefield
Sideline Beekeeper, Oregon, USA
[log in to unmask]