I use the type of rig you mention, but put the feeder on the line first so it is free-running. Then when tying your loops, put a rubber bead inside the big loop. This then acts as a buffer on the knot and when you get a bite, the feeder will hit the knot at the line end of the loop, acting like a bolt rig. Should the need arise, the feeder can slide over the knot and up the line, therefore being free-running and safe.