The AQHA website has the rulebook/handbook online http://www.aqha.com/association/registration/handbook.html
And as with most breed show pleasure driving- a light harness without breeching such as what Hunt’s, Freedman or Walsh makes; a 2 wheeled Jerald or Houghton basket cart (and I believe wire spoke wheels are in style with the stock horse breeds, where with the saddle horses wooden wheels are more stylish), 2 hands on the reins and whip carried if need (for me always, but if you choose not the judge can’t hold it against you) is all standard equipment and procedure. Here are photos from the AQHA World Show Senior Pleasure Driving https://proofs.kcmontgomery.com/index.php/proofs/select/JPI4RPB98D.SRPLDR
The biggest difference between breed show pleasure driving and carriage pleasure driving is in breed show pleasure driving the focus is on presenting the best representative of the breed (the best horse) and class specs while using conforming legal equipment, vs. carriage pleasure driving where you are creating a whole look with horse, harness and carriage that is being judged as a package. My advice is don’t get your undies in a bunch if the breed show thing is different than what you have been doing, it is not wrong, it is what is acceptable in this area of competition. Either adapt your style and help a friend enjoy driving in the area they would like to pursue or point them in the direction of an instructor who does more regularly deal with this type of driving 