I want to test swapping driver but it seems you can only do this by getting someone else to join the server and do it live. The only way I have thought of is to install rFactor on my other computer but a) I'm not sure that will work because both "players" (me) would have the same Steam ID and b) it means downloading all the workshop content as well as the game.
It's not possible. If you try to launch a second rF2 in a different computer with the same account, the program will ask you for closing the rF2 already launched.