I have been sold on ARB for more than 25 years (my first D30 ARB is in its 4th, or 5th, vehicle).
Yes, its too small an axle but the locker has never failed; even after the tire diameter changed/evolved from 31 through 35 inches over the years.
I have 2 of the old style (3 piece case) ARB, D44, air lockers on the shelf waiting for the next axle change (& eliminate the rear Detroit locker; a big improvement in the snow/slippery).
I don't understand folks that intentionally use a ring gear smaller than a, old style D44 (8.5") on a light weight vehicle, without planning to change it; but everyone is different.
Trying to use a revers cut ring gear in the rear will probably be up to 33% weaker than using it in the front. Although we have done a couple of reverse cut custom 60s (Currie rock jock center section) in the back of light weight low torque rock buggies with 40 inch tires...I always kept my fingers crossed.
Enjoy!