Didn't they clear over the tank decals from the factory? When I was building mine I had picked up a set of tan plastics and got a tan tank from ebay that needed to be repainted. It had clear over the decals and I had to sand them down first to remove the old decals so I could finish sanding the whole thing.
That could've just been on that one tank, though. Maybe the PO did that or something. I haven't even thought to check my green tank since it's in good shape and doesn't need any work.
I forgot about the clear coat , I think your right ?, but, with a razor, and a steady hand, a person could trace-cut the decal out line, and still use a heat gun to get the decals off, I would think so anyway ?.