I actually added about 1/4 inch of additional fiberglass along the bottom edge of the cutout for the window. Mine must have been the first one off the line because the windows just barely covered the cutout. I wanted the screws to go through the fiberglass and then into the inside trim as I felt this would provide a better seal than just sandwiching the inner and outer frames around the fiberglass. It is a two person job, one inside and one outside with lots of careful caulking. I probably spent about 3 - 4 hours on one window all said and done, but I am particular. Lots of time cleaning old caulk. Oh, you will have to bend the frames to conform to the curvature of that hull section. I bent mine between the framing members of the trailer, you know how that goes, bend, check......bend a little, check,......bend a little , check, many many times until I was satisfied with the fit. You will not likely get them perfect, but they will pull in when you insert the screws. If you have a hard top, you will need to get creative removing and installing the screws behind the pipework, about an inch of space to insert a driver to remove the screws. A pair of windows for $70 is a steal as well!
