I took another route and added my fantastical fan in a new hole in the front.
That gave me TWO vents, left the orig as stock and the new vent is in the front where the ventilation is kinda poor on my Scamp
13. Also, since it's in line with the kitchen window, range top and door, I can open the kitchen and door windows
and suck out all the cooking odors and fumes.
At night, the fan is up front and away from my bunk in back, so the noise is less. Only problem there is that I have to get up to manage the controls -- Need a remote!