I wanted to make sure my panel was as close as possible to the window to catch as much sun light as possible.
So in Bondo style a couple bungies and some pipe insulation foam does the job. pull the curtain back over it and you don't eaven know it's there.

Pipe insulation foam is also great for sealing up the top hatch board to the sliding hatch to keep the wasps out, and any edge that is rough like the tops of the bulkheads in the aft storage.