I put the handle of my action wrench in a hole in the top of my bench. Then I slide the nut wrench on and connect my 1/2" ratchet driver into the square hole in the nut wrench. That makes the combined length about 30". Just takes a tug and the nut pops loose.

To install the barrel/nut, I use the same setup, and have to do a little trial and error to get headspace just right. Lately it takes only one or two tries, cause the barrel will spin a little, but no biggie. Just check and recheck headspace. I would do that no matter what method I used to install it.