Wearing your respirator, scuff the entire motor home using a coarse grit sandpaper and follow up with a fine grit sandpaper. Make sure the entire surface is dull and smooth to the touch.
Wipe the entire surface with a clean rag and acetone. Remove any grease, oil, or dust from the surface. Anything left on the surface can affect the gel coat finished surface.
Tape all windows and trim using painter's tape. For the windows and tires, use thin plastic such as large garbage bags. This is important to avoid any unwanted over-spraying.
Starting from the top of the motor home, spray on the first coat. Don't make the first coat too heavy; just give it a solid misting. The first coat should not cover all the way. Let the first coat get settled and then apply the second coat. This coat should cover the rest of the surface. Avoid runs by being consistent when spraying the paint. If necessary you can add a third coat, but if done carefully, two coats will be sufficient. Let cure until the coating is hard and cool to the touch.
Clean the gel coat gun with acetone before the gel coat hardens. If not done every time, your spray gun can harden at the tip and be ruined.
Take the tape off the motor home. If there is tape residue left on the trim, use a little bit of acetone on a clean rag and wipe it off.
Add two to three layers of boat wax and buff out for a shiny finish. The wax also acts as a protective layer for the gel coat.