I am sure others may have better ideas but I would consider getting a marble tile for the "cool end". Marble stays cool and pulls heat away from the body (note tile floors will warm up, but marble always seems to be cool even in 80-90 degree temps).

I do run AC (but not central) and I worry about the same thing. May head on down to Lowe's or Home Depot and pick up a couple, then stack them.

If you are tight on cash (Can't recall what marble tile costs) and you live in an area that has granite countertop or marble bathroom counter fabricators (usually small shops that cut/polish granite/marble for custom jobs) you might swing by one and ask if they have any small broken pieces that you can buy cheap (or they will probably just give you some scraps). Do a search for "Granite Kitchen Counters" in your area and you can probably find local fabricators unless you live in a small town.