Don't over-fill the keg and submerge the gas dip tube?
Two things:
- one can cut gas dip tubes down to 1/2" total length which will provide a significant increase in over-fill margin.
- all gas lines should have check valves (aka "backflow preventers") somewhere beyond the regulator. The regulator itself and ideally any manifold should have shut-off valves with integrated check valves...
Cheers!