Transporting in HOT weather help needed by 7/5/12 6pm EST

Here's the CHALLENGE:

My brother wants me to make a BC iced cake. No problem, HOWEVER, he needs to transport it to work, 1 hour away, IN HIS TRUNK, IN 90 DEGREE WEATHER. Does anyone out there know if this is possible, maybe using Dry Ice in some way?

This is a 1 layer sheet cake 18x26 sitting on 1/2" thick foamcore. The cake will be sitting in a HD cardboard box bottom that I made, with a piece of plastic covering the opening.

Thank you in advance

Thanks to all who replied! As it turned out my brother was going to be working a day shift which meant that I would have had to meet him at 3:00 in the morning (YIKES). I was ok with that; CAKE DECORATORS do whatever it takes don't we? Consequently, he asked his co-worker to drive from Ohio to pick it up, which he did. Either the guy was smart and opted for this plan or his wife opted for this plan for him LOL . What a guy either way.... problem solved! Prior to that I told my brother to measure the width of the car door opening to see if the 27 x 22" wide box would even fit, if we wanted to put it on the back seat, resting part of the heavy duty cardboard box bottom I made, on a cooler he could set on the floor. I also had called to get a price on dry ice ($16ish for a 12" slab) and some approx. usage directions. Part of that problem/equation was that I didn't have another piece of cardboard to make a little larger box bottom to set the smaller box bottom into, with dry ice underneath and covering both with plastic. Plus, the lady at the store recommended I pack regular ice around the dry ice as a cooling effect vs freezing effect.

Consequently, one of these days soon, I'm going to buy a small piece of dry ice and experiment with a couple of 1 layer 6" cakes; dry ice above a box and bag-covered cake vs dry ice underneath with regular ice in contact with it. I'll have him be the guinea pig/do quality control on the taste & texture on the cake and IF it freezes at all, how long to thaw.

Funny, never using dry ice before, I have to admit that I did wonder if the vapors from the dry ice would seep out of the trunk at all and make other drivers think his trunk was smoking (like at stop lights) Hee hee