Its not that bad!
I had four coats of clear on the vette and ended up with average mil reading of 16-18 mils, measured at r-fender and left quarter with dummy piece of metal clamped in wheel well.
With 600 I had from memory APPROX 11-12 hours.
Then with either 1000 or 1200, about 2 hours.
Then with 1500 about same or less but had a few phone calls, so lost track.
The course grit makes or breaks the job, the finer grits do nothing but convert the scratches.
You will win!!!