You may find that if you park the boat in the sun, a hair dryer is all you need to remove the decals, plus the goo gone. I wouldnt buy the other stuff until you try that first.

Start wherever the decal is already starting to come up or where you can grab an edge.

Cynde at Atlanta Marine gave us a deal on the decals last season. I think it was under $400 for both sides & transom. Tell her you are from the forum and see if she can do that deal again.