You should be able to take the load off as you describe. If you get it just right with the wheel still on the ground the spring will be in a neutral place. Worse case you may some weight from the spring and some of the rear end weight to deal with but it should be fairly easy to take apart.

On my truck the same thing happened except the shackle pin was out about an inch and a half and the side plates were bent and the tapered hole ruined. The shackle bushing was shot but fortunately the forged frame part was undamaged. Interesting that both of our problems only occurred in the left rear.

Chuck