Using 80 s/p, form the door gap to a uniform 3/32". The procedure I used was to sand the flat surfaces using an RO sander and 120 s/p. Doing this produced the cabin top and door channel surfaces. Next, I started with one piece of 80 s/p and ran in around the door gap, placing the cutting surface of the s/p against th cabin top door channel. This allowed the door edge to be a template for the gap. Subsequently, I added layers to the s/p to increase the gap to 3/32".
Once both door gaps were satisfactory, I applied a thin layer of epoxy/micro to fill any pinholes. Next, I will finish sand the surfaces and apply a thin layer of epoxy to seal the filler.