I did one sort of like that in my
scamp 13. Key considerations are things like how are you getting enough cool ambient air in, getting hot air out, water drainage, and just making everything fit. I also wanted to minimize holes in the exterior
fiberglass so I went out the bottom.
View from the outside is below. The arrow points to a minimally visible vent.
A thread with more details is
here. Feel free to ask questions if I can help.