I cut out a thin piece of clear plastic, almost the thickness of something like a pop bottle, the same size as the sticker and then stuck the sticker on the plastic.
Then I put double-sided foam sticky tape, the gray stuff meant for outdoors, on the back of the plastic and stuck the whole thing to the lower left side of my windshield on my Road King.
It is easy to take off and move if need be because of the foam tape. You can peel the whole thing off and move it somewhere else if you need to, or just leave it be.
Anyone that's tried to remove the DOD stickers knows they usually come off in little pieces. This way you remove the plastic "plate" with the sticker attached. Works for me and the gate guards!