I'm not necessarily advocating it, but you could imagine a weight limit system where the weight of driver was taken into account. Something like:

total weight limit = 880 + 0.4 * ( driver_weight - 160 )

- 120 lb driver - weight limit: 866lbs (746 for crew)
- 160 lb driver - weight limit: 880lbs (720 for crew)
- 220 lb driver - weight limit: 904lbs (685 for vrew)
- 260 lb driver - weight limit: 920lbs (660 for crew) 

I don't know what the right values in the forumula would be be to make things even ...