i shouldve of taken a pic of the deck patio mount we have in our warehouse. i dont know why that cant be used? it has a faceplate to mount on the deck, and a pole to support the dish. it is awesome mount. i have used these more than having to use a pole mount when a customer says they dont want it on the house... most houses have Decks. i have NOT come across a house that didnt have it. most apts do have them and they have beams to support the decks.. even if you lived on the main floor with no deck. there are supports to support the upper decks above you. i wished i had kept that deck mount.
they are more useful than the pole mount or even putting in a 5 gallon bucket full of cement and using that, it doesnt take much for a high 20 mph wind to blow that over.
You are right about the bucket not being very stable. The available railings to attach it to aren't always all that strong, either. My suggestion of using a pole was in reference to putting them in the ground. For this situation, a sled type mount held down by cement blocks might be best. I don't know if there is room for it, though.