Rats have considerably larger droppings and WAY more urine than mice. So if the droppings are quite small, it was probably mice.
I would clean everything very well and set some good old fashioned traps to get any that may still be in there. I made the mistake of leaving poison bait out in one of my trailers years ago and a rat ended up dying somewhere in a furnace duct. The smell was absolutely horrible and we never could get rid of it. From that point on, I concentrate on keeping rodents out and trapping any that may get in.
Good luck and let us know how you make out.
2013 Ram 3500 Megacab DRW Laramie 4x4, 6.7L Cummins, G56, 3.73, Maximum Steel, black lthr, B&W RVK3670 hitch, Retrax, Linex, and a bunch of options incl. cargo camera
2008 Corsair Excella Platinum 34.5 CKTS fifth wheel with winter package & disc brakes