Thanks for the advice everyone. Unfortunately, because of the humidity, water doesn't evaporate very well. My boyfriend recently started working an outside job (he's the guy at the Walmart Tire & Lube Express that puts all of the customer information in the pda, in addition to helping with stuff like checking air pressure, moving cars in and out of the bays, changing wiper blades, etc) and it's brutal already. When he wipes his face, he'll literally have a pool of sweat in his hand that will go down his arm and fall to the ground, because the air is so humid that it won't absorb it. I'm guessing that wetting Ein down won't do much good if the water can't evaporate, but I'll try just in case.
Mostly, we've just been keeping him inside where its airconditioned, and only letting him be outside long enough to potty or get the mail. Every once in awhile, I take him with me in the evening when I go to take Lucas a drink at work, but it depends on how hot it is. I stop at a gas station to get Lucas an Icee (soda/water/gatorade doesn't stay cold for more than a few minutes, so I get him Icees so that it can cool him down better). I only have to be in the gas station for 2-3 minutes, but I still don't like to leave Ein in the car for even that little bit because I'm afraid that even 2 minutes in the car with the windows down is enough to make him extremely uncomfortable and cause harm. I only take him with me if it's recently rained and the air is temporarily cooler (which pretty much means that I've only taken him with me twice). He loves going in the car with me, but I just don't think it's worth it to risk him getting too hot.