Ya idk wats with the grasshopper stuff lol but any way listen i have the same setup as u, same netpots. They do take up about a gallon of space un your 5 gal buckets and u are SUPPOSED to keep water level just under it. But even with that i still fit about 3- 3 1/2 gal of solution in there and u can go over the netpot if u NEED 2 and consider how much it drinks in one day.
i doubt u will rot the roots or have problems if u fill to about 4 gal and go over the netpot a lil bit since u know it will drink it by the next day and hopefully limit the chore of adding water from every day to every other day.
As long as its drinking it and not just sitting in it u should be ok i would add more water at a time.
On a side note super stoner is a f`in genius a 2 in net cup would make a 5 gal res seem much bigger and eliminate this problem. I think it would save money 2 since our net lids cost me 6 a piece and 2 in cups are like 50 cents. I get the grey buckets at lowes u could just buy the lid with it and drill a 2 in hole and pop it right in. Ill say it again, fuckin brilliant. Only one question how sturdy are your plants in such a small cup, is it supported? Have your plants tipped at all or anything like that? U said u had a 6 foot lady in one of these like that?