A "rear entry" action wrench if you must. Nothing wrong with using "barrel blocks". I have a Wheeler action wrench that I used one time. Never again!!
Clamped it around the action. Broke the nut loose. Tried to turn the barrel but all I got was a squeaky noise. Had to loosen the wrench so the barrel could spin. First and last time it got used. Costs more to ship it than it's worth or it would have been gone "long ago"!! Distorting the action so I could spin the barrel off?? I DON'T THINK SO!!
I don't bother to use my blocks anymore. Clamp the barrel in a padded vice jaws, pop the nut loose with it's wrench, spin it out. Done deal. Reverse the procedure, setting the headspace as you go. I've lost track of how many times I've swapped barrels on my rigs. Replacing a barrel for the first time can be a PITA. After that? Smooth as silk.