I have the F5 on my acrylic tank. My tank is approx 18mm or little under 3/4". It works pretty well but sometimes I wish I got the F6. I can scrub my tank with one hand using this. I believe my tank was similiar to yours where it got so bad that I couldn't see thru it anymore.
I started with using a stainless steel blade for my kent scraper. The acrylic one couldn't remove the coraline algae that was built up due to years of growth.
Anyway the scratch removal kit works pretty good. Start with the roughest grit, trust me. You'll just be wasting time and wearing out your sandpaper using a finer grit in the kit. The cutter bag / dozer pad won't make a difference with the issue I can see on yours (I tried doing that first on mine. ). I still recommend you buy it, the dozer pad is great to scrape coraline on a regular basis and the algae cutter bag works really well and makes maintenance easier.
BTW i repaired my tank with all corals and fish in tank. No loses and the tank looks new!