Oxy/Act welding setup safety

I am adding two regulators to my welding system for welding aircraft
parts with a little Smith Airline torch system.

I was able to but two excellent new Craftsman acetalene regulator ver
y cheaply.

I am going to add these regulators to my little portable welding table
and rig my hoses from the tanks to these regulators.

I'll step down the oxy to app. 50 lbs. pressure to make a dual stage
system.

I am planning to step down the acet to 15 lbs as the accepted maximum
for delivering acet gas from a cylinder. I'm worried 15 lbs might be
too low to properly utilize the second regulator and hold accurate
pressure and flow for OA welding.

Can I step down the first regulator to feed the second regulator to
say 50 lbs as long as I always flow at low volumes under 15 lbs from
the second regulator?

The second step will be only for low flow 3-6 lb welding torch
settings. Anything higher in flow or pressure will be run on the
primary regulators as usual.

I've seen banked systems in the big heavy equipment shops from my
early trade but never really studied the systems. They consisted of
many tanks piped through big regulators to supply pipe then stepped
down at work stations.