Agree with the above and especially about taking ALL food items out including soaps, toothpaste and such items. Also, clean the camper from top to bottom inside. We also leave dryer sheets in and around the inside the camper to supposedly deter the mice(if nothing else it makes the camper smell nice). I spray the under side and legs/tires of the camper and garage area with pesticide too. If you have a grill or other food related items in the garage, either clean or remove them.
Remove batteries from smoke and propane detectors. Close all shades/blinds so the fabrics don't fade. If it is that long term I would also add a cap full or two of veggy oil to the sink/shower drains so the winterizing solution will not evaporate out the "P" traps stinking up the place. Maybe add it to the toilet to keep the seal from dry rotting too. Make sure to wipe up all pink solution out of the sinks and shower as it will stain.
Make sure you drain the water heater and remove the anode rod/plug.