Profile of The Ashigaru

I definitely agree that Rifle Company is the most consistent American doctrine versus Ostheer OR OKW. Borderline OP if it isn't actually. Like you said, it has pretty much everything needed just from the call ins. Plus you forgot to mention the flamethrowers...

Best advice I can give is playing very carefully and always have infantry supported in the rear with MG42s at key points. One advantage you have is some early game capping because it takes longer to deploy vetted rifles. I think in general the rifle company will be slower coming out with most things. You should be able to get an Ostwind out long before the EZ8, for example, which will be a hardcounter to the vetted inf unless he puts bazookas on all of them. For the lategame, maybe try a Pak 43 (very map-dependent), or an Elephant. EZ8s need to be disabled and then destroyed at range if possible. Regular Paks are very vulnerable not just to the tanks themselves but to the phosphorus barrage, so while one might be good, don't stock up on them.

Also, mortars are strong against the US in general (imo) so be sure to use them and keep them safe.