One of the techniques I use is open the bleed valve on the caliper and let the system gravity bleed before I start the normal "press and release" bleeding. But, I have a high mounted MC.
So, I was doing some more reading on low mounted MC's and I read some posts where guys were doing one of two things to replicate the gravity bleed: 1) jack up one end of the car to make the MC higher than the calipers you're bleeding; or, 2) Unbolt the calipers and let them hang lower than the MC.
Two more questions...Are there any places in the line where an air bubble might get caught and not get pushed through? Also, are your calipers mounted with the bleed valve at the top?