hop on the monorail and go on over to Poly, GF or Contemporary and grab a drink in the afternoon and relax in one of the lounges? thats what id recommend. then get yourself back on order to MK and try and hit some of the indoor aircon attractions like Tiki Room Country Bears to cool off.
there are also lots of places to rest and relax on Tom Sawyer Island!
i have been to Tom Sawyer island and sat and actually read some of Adventures Of Tom Sawyer By Mark Twain - it just feels right reading it on the island lol im a big geek! lol