By all means borrow the magnet idea. I will suggest using rare earth magnets that are rated at 20 lbs. or more. I initially used two small (maybe 5 lbs.) magnets and they wouldn't hold the Christmas topper in place. It would stay there as long as the piece wasn't bumped or moved. I purchased a dozen 40 lb magnets on Amazon for $15.
As far as my niece, she has a horse tack shop and a lot of people come through. I figured if I gave the Welcome sign to her, she could tell her customers who were interested that I would make them to sell. She also suggested I make some western toppers. (Horse heads, riders, boots, cowboy hats, etc.) My only problem is I've been busy doing this sign and toppers and haven't gotten to a couple Jim Blume patterns I've been wanting to do. Just not enough time.