I would personally be open to permitting the carbon front body clip in all classes, as well as permitting reinforcement for the body. Many often double dip bodies if they run on larger tracks, and the stock front clips break if you look at them wrong. A carbon or alternative front clip is not a performance enhancing part, but increases the reliability of the car. Much in the same way as permitting the aluminum t-plate mount, it prevents wear and tear on the chassis when changing bodies and body clips. I usually use long machine screws with a nut on top to secure my body clips, which prevents it from stripping out the holes in the chassis, but also makes it difficult to swap stock body clips when needed.

as for wheels in the box stock class, these should be 20mm only, as it is within the spirit of the rules to stay with stock size wheels in that class. The stock class should permit 17 to 22mm wheel size of appropriate width for front or rear. Stock class has a more open upgrade option, but box stock is minimal in performance upgrades and really only permit reliability upgrades to keep cars on track.