What is your method of dealing with your hot fryer oil in a mobile unit?
Drain it into a metal container? This would be a little dangerous while hot, but a good opportunity to filter the oil before every use.
Build a cover that seals the oil in the fryer, or at least minimizes sloshing, and prevents spillage on the road?
Wait until it cools (how long will that take for a 45lb fryer?), then strain/drain it into a container