I agree w/ OP. Perhaps the lean key could be mapped to this purpose, seeing as it was unused post MG-deploy in Ost.
In practice, the gunner of the MG at least in the case of the Mg42 could choose a point where he would attach his bipod to.
I think this is not the case with the 34, which appears to only have one fixed attachement point at the front of the barrel (please correct me if I am wrong here, but i have never worked with the 34 so I can only derive it from images and research)
But in the case of the 42, it means you can choose your "swing radius" by either attaching your bipod further to the front of the barrel or farther to the back.
Back would mean larger radius and front would cause a smaller radius. Maybe bipod attachement customization might lead to a solution to your problem/lower its effects. (this might decrease your accuracy though)
Because otherwise you could for ex. also ask for an "ironsight" customization in order to set the distance you are reasonably, accurately shooting at with your MG. Despite the fact that i could imagine that the latter could be easily implemented similar to the tanks sight adjustment.