Thanks to pomigit for releasing an addon that allows you to add a squad specific patch to the baseball caps. You can do both a forward or backwards cap. I have modified his work to add the [RR] logo to the baseball cap. You can download it here.
To use the addon you can simply type the following into the initialization field of your unit:
this addHeadgear “RR_BackCap_Red”
Front facing caps:
Backwards facing caps: