Love learning what goes well with crayfish!
It seems that if there is adequate space from the top 1/3 of the tank without perches/DW, rock for the Cray to hang out on and get those claws up possibly to snap some part of the fish, you would probably be alright. Although I am somewhat familiar with crayfish, I am not particularly familiar with the DPC. So maybe someone actually know how this would playout.
Somewhat depends on the nature of the cray. Aggressive to shy. Do you have an idea about how yours is towards any other fish???