I wasn't sure if the OPs intention was to solicit how to even out Hunter PCP vs Hunter Piston, or to bring parity to Hunter vs other Divisions. PCP has some inherent advantages over Piston, so we would need to handicap the PCP in some way in order to achieve that first goal.
Back to K (Knobs):
10) might help scores and make it less work for the Hunter shooter, but it does not encourage development of ranging skills.
Most all "Hunter" field target shooters us mil-dot scopes, or some other stadiametric reticle. Those reticles are designed specifically to range known targets. Give the the shooter something that they can use to practice their reticle range finding. Some standard sized features or maybe a cheat sheet with some target sizes.
In many cases, those "in charge" do NOT want the Hunter shooters using the scopes as intended, or they just want to keep the Hunter scores lower than the Open shooters. If that's happening, you will not have scoring parity with other Divisions unless we allow the same equipment.
What I have been doing at our matches: I do not go to extra efforts to cover targets or bases (at least most targets
). We use only 7 different face plates, with the majority being the ubiquitous squirrel target. The Hunter shooter can learn to apply stadiametric methods and get some semblance of parity for accurately ranging targets when compared to higher power scopes. I encourage it and have even done presentations at past matches on how to utilize that method of range finding. But I also tell shooters not to rely on that method, and that focus range finding can work for close targets when needed (and farther targets if they have a high power scope).
You may see matches where extra efforts have been made to hide targets/features, and the bucket-sitters/bipod-users are not allowed to use high power scopes (no freestyle). Those match directors do not want the Hunter shooters to have parity, so accept it and it's OK.