Which side should rough wiring for roof ac be on?

We are converting a cargo to toy hauler. We have a donor camper for the AC, fridge, windows, and couch. However the donor camper is an hour away at the lot and the cargo trailer is at the shop where we live.

We are putting the ceiling in the trailer now and can't get to the donor camper until this weekend at the earliest.

All I need to know is should the romex wire be routed to the front or the back of the AC unit? I am not sure the brand, but I'm sure it's a dometic.

I just dont want to drill through the steel trusses when I can route the wire along the wall to the correct side of the AC unit without drilling if possible.