I've kept my miliaris together for months at a time during the breeding season just to make sure he gets the job done. I separate for feeding, but now it looks like they are going to be separate more often!
Strange too, as I just finished reading the Rodriquez-Robles et al paper about gape size in Erycine snakes which list published reports of feeding in E. miliaris (and other erycinae). They list 10 species of lizard, 3 species of bird, a bat, and nine rodents, but no snakes! Guess miliaris can be flexible!