It depends on the kind of powder you shoot and what you treat your bore with.

If your shooting Blackhorn209 then you have to use solvent. So alcohol would work real well.

If you are shooting Pyrodex RS or Triple Seven, why not take a small bottle of soap and water with you and a bottle of alcohol. You could use the soap and water patches to take the majority of the fouling out of the barrel and the alcohol as a finishing touch to be sure it is clean and to help dry the barrel. After that some dry patching and then oil the barrel again.

If you are a bore butter shooter, use the soap and water, then dry patch the barrel and be sure to pop some caps or primers through it for the next day hunt, before you load. Do it the night before and you do not have to do it in the morning and risk spooking game.