Got a couple different types but one common problem is rain runs down the wall and ruins the floor. Anyone have ideas or suggestions to modify and keep the rain out?

Have a 5x8 have not had that issue.

What I had to do to keep some plywood walled blinds dry ( and it would work for fiberglass), was to make some small awnings (for lack of a better word) out of roofing tin. Cut them to the necessary length (window width). Bent them longways into an L shape. Mounted them above the windows with screws through the walls into 2x2’s, and I used a construction type black glue/cement in addition to the screws. No rain problem since. Took me a long time to figure out how to make good rain diverters.

You will need an assistant and some air driven tin snips.

I have these over all my blind windows and doors. Works well except for with a wind driven rain.