Plugins for Photon?

Is there a way I can write code to run on my game’s servers (hosted on Amazon EC2)? I don’t need to do anything too intense like simulating physics or unit stats. I need to use the server as a middle man to process commands for my lockstep RTS game.

What I wish to do: Every time a client tells a unit to move, the move command will be sent to all players. Every player, upon receiving the command, will send a confirmation message to the server. Once the server has received confirmation from all clients, it will send an RPC to all clients to let them know that the command is ready to be executed. If not, it will send the ID of the player who is not confirmed and a voting screen will pop up to vote that unconfirmed player out of the game.

To accomplish this, I will have to 1. Have an RPC on the server to be called for confirmations and 2. Send an RPC from the server if all clients are confirmed. Is this possible with Photon Unity Networking?

Do I have to edit a certain script or insert my own into a directory?

This can be done in the room.cs file in the photon server sdk by following this tutorial: Fusion Introduction | Photon Engine.