The wire stands that came with my bandit Signs from SignWarehouse would not go more than 1 inch in this ROCKY soil here in MT. The little wires just bent and got ruined. I had to get physical with it.
The tools you need to do the job in HARD soil are no big deal:
-- 2 pound hammer (called a hand drill) with an 18" handle. It's like a mini sledge hammer.
-- 4 BIG nails from the hardware store -- 12" monsters are about $2 each -- 5/16" diameter or so. Get the extra 2 since they can get bent also.
-- knee pads.