Amy, I do have auto turners..My incubators are the cabinet style GQF sportsmans.. I have rigid plastic egg holders that fit on the shelves .. and then the whole shelf rocks left to right..
I figured out a way that I can stack the holders with a little modification to the top holder.. with average sized chicken eggs, I can raise the capacity from 288 eggs to 576 eggs..
this comes in really handy when the guineas start laying .. I usually hatch about 300 of them each year..
I have two of these incubators that I can stack trays in.. the third one can handle only single layers of trays.. I use it mostly as a hatcher..
In the past, when I was using styrofoam bators with turners, I occasionally laid a few extra eggs on top of the ones in the turner.. they hatched OK, too..