I'm kind of in the same spot as Mike. Using 5' lines with perlicks in a collar though.
I've had no problem with foam if I vent the kegs, but I went through a 5# tank of CO2 in 3 kegs (I force carb).
Venting the kegs from 14 PSI down to 5 ish when the keg is 10% full is a HUGE waste of CO2...