You are taking much the same risk you would with a pair of Kings or Indigos. Racers have a taste for snakes. You could likely divide that set up in two and still have plenty of room for each hatchling. Be sure you have plenty of cover, they are skittish at first.
Good luck with your racers, and thanks for posting here. This forum has been dead lately.
BTW, you might try the same post on the Indigo & Cribo Forum. It seems to br the de-facto forum for "Large Colubrids That Aren't Rats, Kings, Corns, Hogs, Garters, or Waters". Seriously, most of the knowlegable racer guys are also indigo fans, so that may be your best bet.
Try paging Sighthunter - he's "The Man" for Coluber.
Regards,
John D.
-----
I am so not lesdysxic!
0.1 Creamsicle Cornsake "Yolanda"
1.0 Bairds Ratsnake "Steely Dan"
0.1 Desert Kingsnake "FATTY"