The whole Wasteland driving is a bit of a mystery. It's strange that all of the Wasteland1 races work, but you can't actually go into the Wasteland for free driving. For the eastern Wasteland, it's a bit odd that some races would work but not others. It has to do with what assests are in which maps when the map is run through the build system.
Thanks for testing. I'd at least like to get this to a state where it only crashes when you goto either wasteland with a special buggy, if we never get the ability to build w1 and w2. Otherwise, it's kind of a broken mod. Works fine if I plug it in at work on the development (non-build) game. I may have to take this off of moddb or put up the non-buggy one for a while.