Since this seems to be a big potential stumbling block, why not automate it?
If there is only one human player (connected, reserved, or otherwise), and that human player has chosen the Champion type, then choose the next available open slot (should be player 2 in this case), make it a Champion player (that is reserved), make the human player a Normal player, and then you basically have fulfilled what people are expecting.
A few wrinkles I can see: player color (as the Champion will be under a different player, an automatically set up one, who knows what color will be chosen for that second "player"?), player name (Who is this "???" in player 2 slot?), and player count (why is it listing two human players when I am the only one playing?)
This would only fire when there is one human player in the setup screen. If there is more than one player (again, connected, reserved, or otherwise), you need to start caring about player assignments and details, and thus you must figure out who will be the "regular" player in this case.