When I started in the truck maintenance business, over 1/2 our fleet still had split rims. First thing I was taught about split rims is to let the air out first thing.

Then the last thing we did was put the air back in after the wheel/tire was mounted on the truck with a long hose and clip chuck.

We did not have a cage, never did get one. Glad those things(split rims) are mostly gone now except for on industrial equipment.

I still mount tubeless tires on big trucks at work and at home on my own RV.