I did mine by myself, in a regular size 2 car garage, with regular height ceilings.
I removed all 4 wheels, and let complete vehicle down onto wheel dollies, resting on the brake drums. You will need to use wood blocks to get your floor jack back out once you lower the chassis down.Then I loosened all chassis to body mount points. I then took a floor jack and jacked up the front section of the body dead center on the firewall, my engine and transmission were already removed. After jacking the front section of the body I went high enough to slide a 6x6 between the body and the chassis. Then I went to the rear, I jacked the rear body panel and went high enough to get the 6x6 between the body and chassis. Once this is completed your 6x6 are sticking out where you can lift with your floor jack and then once you have the desired height set your jack stand under it. This is where it gets sticky. You can't go to high on one corner to soon. I had to go small height amounts on each side working back and forth. Then do the same for rear. You have to get the body pretty high up off the chassis for the chassis crossmembers to clear. I used tall style "SUV" jack stands. I would also recommend you have the complete body bare, with no doors, trim, seats, glass ect. Mine was completely dismantled, not only does it save weight but gives you complete access to everything. I had to bring the chassis out of the middle, like tick tacking back and forth.
I did not access to a lift or a tractor with a bucket to get mine off. This worked. Thinking back on it now I would not hesitate to do this again but I would have had an extra set of hands to help shift and jockey the chassis out.
I did something very similar to this, it worked okay... Just wish I would have had a 2 post hoist!