Single Comment

I still like the Superchess way of introducing a guest piece best: simply
let one of the sides (e.g. black, out of courtesy) decide on which file the
piece will start, and then replace the back-rank piece in that file by the
guest piece. That way you don't overcrowd the board.

An alternative I sometimes use to test unorthodox pieces is to move an
edge-Pawn one step forward, and put the Knight on the square thus
evacuated. This has minimal impact on the character of the opening, as the
Knight can still reach its favored opening square in a single move move.
The original position of the Knight can then be used as starting square of
the exo-piece.