Venting cooking steam outside

Done! I ordered an outside flapper vent and installed it today. I took down that huge and heavy microwave and turned around the fan to exhaust outside. The mounting bracket was still attached to the wall and it made the perfect template for marking the hole I need to cut through the wall. I made a shallow cut about 1/8" deep on the inside wall and sure enough there were two horizontal aluminum braces about 2" apart right across the area and 3 wires running vertical through it too. I decided not to cut the braces and just use the available 2" gap for the exhaust. I drilled holes through to the outside and made a shallow cut for the outside vent. The wires had enough slack so I routed them around the edge of my new vent opening. I then trimmed the new vent to fit between the braces and calked and screwed it all in place. You'd never know it wasn't "factory".

The hardest part was handling that microwave/convection oven. It was a pain taking it down and putting it back up again, but it was definitely worth the trouble. Now that cooking steam and grease will be outside instead of collecting on my walls and windows inside. I've still got to do the flapper magnet (Thanks YC 1) but that's it.

Thanks again to all who offered suggestions and Happy Camping!