Teardrops n Tiny Travel Trailers

Assuming that you have an Engel or Dometic freezer/frig AND you are going to operate it while you are driving and parked, would you add vents or fans to help dissipate heat? If adding vents, where and what types?

Assuming you have added vents, are there any particular issues with road splash or rain?

Would it matter if the galley area is completely sealed off from the cabin? If the galley and cabin shared air flow, would opening a fan eg Maxx Air Fan Deluxe be sufficient in the open position while driving?

As we're talking electric fridges and not propane, running them in an enclosed area is safe. That said, they work by moving heat from inside the fridge to outside of it, so it's best if that outside area isn't too hot already.

As you point out, if it shares the space with your interior, then whatever you're doing too keep them interior liveable will be plenty for the fridge too. If the fridge is in its own compartment (like an outdoor galley) ventilation isn't always necessary. The air space in the galley may be sufficient to absorb that heat without too much issue if you'll be camping in a more moderate climate. For hot areas though you may need to consider venting.

A few options come to mind. While parked simply opening the hatch during the heat of the day is probably sufficient. If opening the hatch isn't an option, and the compartment gets hot from the sun, then vents might be considered. The big challenge with vents is keeping dirt out. Options include keeping the vent up high (i.e. roof) or using a vent with a flap or filter. Keep in mind though that if you're exhausting air, replacement air is coming in from somewhere, so either that's a different vent, or cracks/gaps in your construction. Either way, that's where dirt will come in, not so much the exhaust vent.