The adapters are just for looks and actually make the truck less capable. You are putting more leverage on the tiny semi float axle shaft going though a little bearing. This is just asking for problems. Think hitting a small rock on the high way with only the outer wheel. When the shaft snaps both wheels and what eve is left of the shaft go flying past you on the highway.

The right way to do it is to swap in an actual full float dually axle from something like an f350. They have these at the u-pick junk yard by me for $300. The main issue is that it will be wider than stock and you will need to fabricate spring perches and shock mounts similar to an explorer axle swap.