@SaturnX said in Adding 2xUSB Gamepads to Arcade Setup for P3/P4?:
What’s the best approach for this such that I don’t muck up my controller settings?
There's not much to do besides connecting the controllers and configuring them in EmulationStation. The only caveat is the controller order - it's possible the external controllers to switch places with the encoders and replace the P1/P2 slots, but if you don't keep the external gamepads connected all the time it's not going to be a problem.
I’m concerned that I’ll mess up the controller configurations and I don’t have a complete understanding of how controller configuration files are set behind the scenes.
Generally the configuration files are matched based on the controller name, unless your external gamepads are also named DragonRise, ... (highly unlikely), configuration files will not be a problem.
Also is it possible to limit the 4p setup to just select games? Is that even necessary?
It's not necessary, you just have to pay attention to the games that have 4p/2p versions and not start the 2p when playing with 4 controllers by mistake (like TMNT / Sunset Riders / etc.).