tire safety cages are fine for airing up tubeless truck tires even better it they are laid horizontal so gravity doesn't come into plat causing the rim to try and seat off center. They are not the best thing for older truck tires with 2 piece rims because you can't get to the bead ring to tap on it making sure it seats evenly for those nothing beats wrapping several 3/8 load binding chains around the tire and rim laying it flat on the ground and airing it up tapping occasionally on the bead ring to insure it has seated properly. But when it comes to heavy equipment tires tire cages even those large enough to contain a large tire have to be made so it is possible to tap the locking ring in place. But I like to do it another way 1 of 2 methods I have used for several decades. One method if mounting a tire with the wheel on the machine is to assemble everything use clamps to hold the locking ring tight in the grove Place a backhoe bucket against the rings to prevent them becoming unguided projectiles, add air until it beads up and forces the bead seat ring out to capture the locking ring, remove the air chuck allow some air to escape while taping around the locking ring to insure it is properly seated install the core put the bucket back against the tire and air it up. I only use self holding air chucks that way my arm is never reaching over the locking ring or the bead seat ring and I can just give the hose a jerk to pull the cuck off of the stem.
For when I have the rims laying on the ground I do it like this . I block the rim up off the ground wipe a small amount of Murphy's tire beading compound on the seating area of the rim and both beads of the tire. Drop the tire over the rim, its weight will seat itself with the assistance of the beading compound, install the removable bead seat ring push it down enough to install the O ring, install the locking ring and clamp it in place wrap the tire and rim with chains then air it up as before.
This is one of the tires for my forklift. It is a baby weighing in at under 500 lbs, without the rim I've done tires weighing half a dozen times that I have never had a tire to blow off the rim while inflating and hope I never do because I'm pretty sure I'm too old to regrow missing body parts.