"Hun, did you exchange your swim trunks for the right size?"
"Hun, did you find some shoes to wear on the beach?"
"Hun, what else do you need for this trip?"
"Hun, did you get your birth certificate?"
"Hun, ___fill in blank with mundane task that he hasn't done yet______"
I think if I preface it with 'hun', it's not nagging. It's gentle prodding. It's just being nice so he doesn't have to walk naked and barefoot in the hot sand.
I did set up a giveaway, though. Something to last you until I come back :)