Just approach his MG positions from at least 2 different sides and there's nothing he can do really since your rifles win his grenadiers at medium/close ranges. If he has a sniper, he usually has one as his first unit so you can just rush it with everything you got - he won't be having MGs until few minutes into the game so you can win the very first engagements very easily by being really aggressive.
Also very easy to outcap the ostheer player since ostheer usually has to focus on a very narrow area of the map and 1 VP during early game to hold his ground. Try play a few games as ostheer and see what the USF opponent does, watch the replays

USF > ostheer in 1v1 imo!