I wouldn't balance USF around LMG rifles. Paras are great but the doctrine is weak. Rangers don't trade at all well until like vet 3 I don't know what you're talking about on that one.
Typically a USF with no doctrine is trying to close the gap against your opponent with your bars. Which means you'll be taking casualties. Plus you're always assaulting to try to close the game out.
Rangers trade well at all levels if they are upgraded with thompsons.
Lmgs are standard for usf nowdays, so yes i would balance them around lmgs, you wouldnt balance grens without thinking about lmgs?
There is no need to close the gap with lmg rifles. At vet 3 they can do it easily tho.
Usf without docs doesnt work, just like sov.