I think your weight minimums are going to self regulate themselves to an extent. It's generally agreed that the mixed teams will have the girl driving and the guy pulling the strings. Is an 80 lb weenie going to be able to withstand the physical demands of the front of the boat? If this is not the case, then the argument for the girl to drive and the guy to pull strings does not hold water. Sure the crews will be small, but I doubt you'll see anything rediculous (that can be comptetitive).