Few years ago, the guys next to us on the campsite had a freezer, which they filled with beer.
They ran it off a genny, while they where there and when they went off around the track they unplugged the genny, put it safely in there motor and still had cold beers when they got back. Not bad, and they let us share them - thats the spirit.
Mind you drinking slush puppy beers was different (need to drink the cold ones first)
Go for a freezer ! - hope this helps (p.s. mines a cold one please, - if I can get a MB campsite ticket)