How do I handle removing this from a plastic pot and into the ground?

Wear gardening gloves and 'cushion' the cactus with a thick wad of kitchen roll, then upend, tap out and plonk straight into the prepared place.

I used an old pillowcase rather than paper towel when I repotted one a month or so back just make sure the gloves are a good sturdy pair!

I usually use a burlap sack, rolled up, or an old towel. An 8" one is also small enough that you could lassoo it with a loop of string, and handle it with that and the roots once it is out of the container.

Good point TugB burlap or hessian sack less likely to allow the spines through.

If it is very pot bound and difficult to remove the best thing to do then is to slit the pot with a stanley knife. I love the idea of hanging the victim in a string lassoo!

That's why I don't do it with a larger, heavier specimen!