JPNola
Veteran
That's the one I own and use. It is designed specifically for the Fs7. The VF fits just fine. By "VF" I mean the monocular viewfinder. LCD display + loupe. ( since, technically, any display used to operate the camera can be a "VF". ) If you operate only from the LCD screen sans a loupe, the Porta Brace cover might not work well for that manner of operating. Or work at all for that manner of operating.
A clear, "kitchen-size", garbage bag might be the solution for your need. You simply place the plastic bag over the camera. cut out a hole for the lens, and trim the excess bag from the bottom. Paper-tape the bag around the lens opening. Cut another opening for the rubber eyepiece cushion of the VF loupe.
The garbage bag method is more tricky if you want to operate from the LCD, sans loupe. There you may have to carefully cut the bag from in front of the screen and tape the bag material around all four sides of the frame. Electrical tape might be better there than paper-tape.
None of the above are moisture-proof. But it sounds as if your issue was spray and not just moisture in the air / condensation.
Consider something as simple as one of those cell-phone cases made of neoprene material. Find one that fits your LCD display tightly and then cut out the image-frame. That would at least provide some protection from spray. You could even use one made by surf-product make Quicksilver ...
This one, with an end-flap, would provide protection for all four sides and also allow the 15mm rod to extend through the gap-
Those cell phone cases are great for protecting your LCD when your camera is not in use. When storing the camera in a travel case with the loupe removed.