I have had fans on my last two campers and they really help. robatthelake says they draw very little power and that is true if you pick the right fan. My last camper I replaced the one that was installed by the camper builder with 3 low power fans with more than double the air flow and less total current than the previous. Mine have a thermal switch which sometimes actually shuts off the fan when not needed but I wired up the 3 fans so I could have the middle one on only, the two outer or all 3 so I could fine tune my current use when camping off the grid. Also helps with noise, not all fans are created equal and this allowed me to run no fan or just one at night when I usually didn't need as much air flow. I needed them most when I had to park or drive where the sun hitting the frig side of the camper. I try to park so that side is in the shade as much as possible.
