I know in my off-road POPUP trailer I have wrap around storage areas from the all the way around the front of one bed under the wrap around seating and down the other wall all the way to the other bed.
I installed those small 2-inch round vents from LOWES between each compartment and then next to the entrance door I flush mounted a 12VDC axial fan. I can turn this on and pull air through all of my wrap around cabinets on the floor. This includes where the hot water heater and water lines run that run under the sink etc as well... I can open the shore power cable access door and pull in outside out air as well...
Roy Ken