Hmmm, the F27 and the F50 are two aircraft i know that have the wings over 6' above the ground and the cabin hung beneath it!! cabin seems pleanty high enough to me!! and with the exception of the odd gear collapse have not heard of them making a trench down the runway!!
The point being that if the wings were AT 6 foot AGL, you would NOT have room for a decent height cabin. Therefore You don't get 6ft AGL wings on high wing aircraft, except for midgets.
The original question put the wings AT 6ft AGL for high and low wing and it's not practical for a high wing aircraft to have a wing that low. You can comfortably walk under a dash8 wing, for example....