I have, and it was a great wreath, but I didn't care about the gate I put mine on! You might want to nail a piece of plywood to your gate or fence before hanging the wreath. It probably wouldn't drain well enough if you put plastic or a type of barrier onto the wreath.

You could also try wiring little "legs" to the back that stick out a few inches to keep the back of the wreath off the door. I've never tried it, but maybe just a "v" shape make out of something stiff like coat hangers.