crazy idea!

[cosworth34677]

OK i live in Florida.... today it was 90 with 100% humidity. in that weather you get over heated quick. so im sitting at the park losing water fast and came up
with this idea.......

what if i made a tanker trailer and make it water tight. and some how insulated it to keep my drink cool!! i was like that would be nice. that thing is how? i can make a trailer pretty quick and easy but the tank part would be hard. i'm thinking PVC pipe but what would i use to seal it and i clean it? putting water in would be easy. but getting it clean would be the hard part.

so any help on this project? good idea or kill the idea with many beers?