Yes, sounds like the handheld may be a good route given the race restrictions- the TomTom models I mentioned all mount to the windsheild.
TomTom makes GPS software for handhelds, thought of that as a gift for a relative who travels a lot for work. TomTom handheld software seems to be well-liked by the PDA set.
http://www.amazon.com/gp/product/B00...Fencoding=UTF8
Hopefully you can borrow some GPS devices/software to test them out- I borrowed a friend's TomTom, it was the GO 300 model, and am really psyched about it. The device is really easy to use- just turn it on and go, no complicated setup.