Flack halftrack or Luchs are great for boosting anti infantry potential.
The key to okw is using your vehicles to support your infantry. A little bit of suppression makes sturmpios a lot scarier because they can't be focused down.
Or really if you need a crutch that badly, the doctrine with mg34 + fallschirmjaegers is a good choice. Falls are extremely high dps at all ranges and have great vet bonuses and an mg34 or two are a bit more reliable than a kubel wagon in the mid game.
Honestly OKE struggles far more with good medium tank play than they do mass infantry. Good Sherman or M8a1 play is the real struggle unless you're damn well prepared for them.
