Originally Posted by
pinniped
(1) Do you have legitimate access to a corporate code with unlimited miles?
(2) Don't most rental agency free day awards include unlimited miles? I know my Hertz and National ones in the past have, but I don't think I ever rented in a place where the "normal" rates didn't... I've done rentals with both solely for the purpose of driving 500 to 1000 miles in 24 hours or less.
Most of the locations in that area will likely be franchises, so free days may not work. I just tried the DL discount code with Hertz, and while it did not lower the rate much, it did give unlimited miles. Try some of the airline discounts, which are easy to sign up for.