Not on their backs. I can't imagine HOW I would have managed if I was trying to do it alone AND get them upside down.
Mine was a shopping bag - so picture looking at one of those reusable shopping bags from the side - with a chicken's head poking out one end and it's feed and tail out the other. I don't know what's magic about it , but the SECOND that I hung the bag they went still and calm.
I just tossed a length of paracord over a rafter, tied it in a loop and snapped a big snap over it and clipped one of the bag's handles in the snap. Then I took a hen, held her legs (yes, she was upside down for this part) and wrapped the bag under her belly/chest - then lifted the handle and caught it in the snap. BINGO - chicken in a sling.
I could trim their bums, inspect legs for mites, trim spurs, apply dust - twirl them around to take a look at their eyes and beak, check comb & wattles, poof some more dust... whatever.
Then I took the sling down and laid them on their belly on the floor & dropped both sides. Most of them had to be shooed out - they just laid there looking around, apparently quite content.