Moving .50cal to T0 while replacing its vet sprint with AP rounds (the MG42 kind rather than the horrible DSHK version) would do a hell of a lot to help both USF early game variety, vulnerability to cheese and viability of this unit.
Then they could implement the M2 60mm or M1 81mm mortar team (which already exist in the gamefiles so adding them should be relatively trivial, compared to creating an entirely new unit) into the lieutenant tier and USF would suddenly look a lot more well rounded...
I do think it's the best solution. An MG that you need to unlock with 50 fuel, and a sub-par AND overpriced one at that, is just not attractive. There are very few situations where I built one and wouldn't have been better served by more rifles, or saving the MP for vehicles.
Plus, US needs some early game variety. Having to build 4x rifles before anything else is just boring for everyone involved. The MG could also fix the US's incredible vulnerability to the Kubel somewhat.