I would save about 20 gallons of water. Fill the rest with new when you get there.
I use rubbermaid brutes or five gallon water jugs. A 55 gallon barrel of water is extremely heavy. I wouldn't attempt it,without a barrel handler and having it strapped down firmly for transport.
You could move the fish in 5 gallon pails. Covered to keep them from jumping. This would be a great time to rehome one of the scats. They get big fast! Also i'm sure you are aware, to be careful of the venomous spines.
I did not know they had venomous spines they always seem to pick at my fingers when I put the seaweed in the tank for my tang.
To all thanks for the input any more sugestions (besides my spelling)????