If all you plan to do with the compressor is winterized your trailer, go with the least expensive which is probably 1 cfm. If you will inflate tires, blow dust out of heating/cooling system filters, air dry stuff, then go with 5 cfm.
2015 F150 2.7 EcoBoost (Big Spot)
2015 5.0TA (Little Elsie)
"What a long, strange trip it's been....."