forgot to winterize and it went to 21 last night

I hope you don't have any other freeze damage....this could be the tip of the iceberg so to speak. The worst will be if there are split water lines inside a wall somewhere. Your upcoming trip questionable.....you may have many more surprises awaiting you. If it were me, after your trip, get your trailer to a RV dealer, and have them warm it up, and test everything for you, then properly winterize it, and then you will be good until spring.