Lainey,
Many of the window cutouts in the
Boler fiberglass shells are too big. The sealing surface is reduced to 1/4' or less in many places. The rear sliding window will drop down about 1/8" when installed, this drop included with the oversize cut will really reduce the sealing area of the window flange. I bond a 1/8" strip of aluminum to the bottom edge of the
fiberglass shell cutout. This strip will generally be 1/4 - 3/8" high and will raise the window up and give you additional sealing area at the top of the window. The aluminum strip is almost full width of the window but stops short of the radii. I drill several 1/16 dia holes in the strip, place the strip on the
fiberglass and drill into the fiberglass. I bond the strip with 3M 5200 polyurethane adhesive and push 1/16 dia brass rod into the drilled holes and clip off any protruding rod. This locks the strip into place and when the adhesive cures it is rock solid.
I am in the process of fabricating fiberglass gutters that are the same shape as the aluminum one that is over the door. I will bond these over all of the
windows. There were several classic trailers at a car show that had the same aluminum gutter over every window. Some people have used double sided high bond tapes with vynal "J" channel over RV
windows.
Good luck,
Rick