Gel coat thickness

[Fainlts]

I have spent the last five nights almost 8 hrs each wet sanding my boat. Started with handing sanding and small palm sander 400 in some areas on to 600, 800 and 1000. I have made almost no progress in removing all the oxidation or restoring the color to match where the decals were. I found a local gel-coat guy with experience sanding w/ DA and was able to show me his work on a small area of my boat. He said" this was the hardest gel-coat he has ever seen". I think I will let him take over for $600 price tag and complete my failed attempt. His question is what is the gel-coat thickness specifications? He would really like to know how much depth he got to work with (mil). I have a call into Skiers Choice since yesterday, but no response. My boat is 2003 Supra Launch LTS - navy Blue.:o

Thanks W. Fain