Does this concept need to be tweaked? Certainly. Could the general idea work? Certainly. The I-8 format would likely become the norm: Soph-Varsity on Friday, Freshmen on Monday. You are going to lose the ability for sophs to get varsity experience in blowouts, and the freshmen who play on the soph team will be limited to playing one way on one of the levels. The one play rule, questioned by someone who says the backup QB plays one play when the starter loses his helmet, means that he played only one way in one game, so he can play in the other both ways - as long as it is not Fri-Sat.
There will be two types of rebellion: first, big schools with JV programs will have to tweak the Fri-Sat schedule. I presume that will be difficult, as playing Monday doubleheaders Fr-JV would recreate Friday night. And kids who play only special teams on Friday couldn't play Sat. So if a coach has to choose playing scrubs in a Friday blowout or have them play the Sat. JV game, somehow the poorer programs will be even more embarrassed when the end of the bench can't run out the running clock....
Second, Fr programs will become more difficult. A program like Wilmington, for example, where the best Fr will start both Fr & Soph, will be hurt in some ways, as presumably the Fr will only be able to play one way on Monday. But it will build depth, as more Fr will get to play significant time in the Fr game. So, again, you may hurt the poorer programs because this rule will allow the better programs to develop more Fr and give them more playing time...
And I figure this will have little effect upon the really small schools, who only have 40 kids in the whole program Fr-Sr, because everyone will dress Varsity on Friday, and the scrubs will play in the Monday game...