Venting an air conditioner through marine ply which is replacing a window.

I have one of those log cabins, double skinned walls, well insulated, carpet all that stuff. What it doesn’t have is an air gap so it gets really warm in summer, the sun shines directly on its black rubber roof. I have a portable air conditioner which also works as a heater. The hinges on one of the windows that was supplied with the shed have failed so at the moment that window is just pushed into the gap and held in position using a couple of braces.

I plan to lob the window and replace it with marine ply. I’ll cut a hole in the ply for the exhaust and condensate pipes of the air conditioner and seal the holes. I’ll then have an air conditioner for summer and a heater for winter.

I may be wildly over thinking this but it occurred to me that getting two thinner pieces of ply and glueing some kind of insulation between them might be better than just one thick piece of ply.

Would that be overcomplicating things? Would it create condensation in the gap that might over time damage the wooden frame of the shed?

Any advice or ideas would be gratefully received.