I used to commute in Tokyo in summer so we are talking about 36-40 C and humid as hell.

I used to take a wash cloth about 1ft square and a bottle of 70% rubbing alcohol. strip off in the toilet cubicle. Spash and wipe on the cloth = squeeky clean (and cooler). I think a bottle from X-Marts are around 50 cents. 1 bottle will last about a week or so. Its cheaper and more eco than baby wipes.