What if we rethought the design of the "rover" to make it smaller and the whole launch mass less? I don't think there's a requirement for a four or even three wheel rover. Instead, we could use a clear double inflatable ball with an instrument package and a motor inside. This allows for a < 10lb/5kg rover. We could pack dozens of these in several rockets to the moon. Redundancy would be in our favor. Kind of like moving from big-iron servers to farms.
This is my inspiration for the double inflatable ball: http://www.hammacher.com/publish/72182.asp