Really unique take on the raft problem! Unfortunately I'm not very knowledgeable in chess so I didn't know the movements of certain chess pieces, led to quite a bit of trial and error on my end.
I also found it difficult to place the potato down, felt it would only register where I wanted to place it some of the time. For some reason I couldn't place it anywhere on the right board - every time I tried it would place where it last was on the left board. Other than that though, I really love the concept and you did well with it, nice job!