Not something I would be willing to try. Why not use hull cleaner in the first place, surely the saving isn't that much.
I looked at a boat for sale which was only 4years old where someone had used some sort of acid to clean it up for the sale which had taken much of the gloss shine off and left patches of small pin holes in the gel coat (not a rib).
I've always been under the impression even the abrasive fibreglass boat polishes were prety much a one off use. Our boats can suffer quite heavely from sun damage over here so things may be different to how many times these can be used. Most newer boats have good uv protection within the gel coat now.