Grind nonskid off while keeping it flat

[We we]

I’m in the process of stripping topsides down for paint and can’t seem to find an easy way to get all that non skid off. I can’t believe how hard this stuff is. It’s molded in the boat and there is some damage in five or six places. There is no way to match this pattern if I wanted to. The plan is to take all of this non skid off and roll on some paint and put sand like particles. I can take a side grinder but I can’t keep it flat. I know I’m in for a lot of fairing, but would like to keep that to a minimum. Belt sanders work but are much slower than I think it should take. Any suggestions?
Thanks.