Deana, we used the pencil circles to mark the edge of the air cell. This helped us point the eggs toward the window during lockdown so we could have the best chance of watching a pip/zip. In previous hatches we had marked the air cell each time we candled, this time we only did it on day 18.
As far as turning in egg cartons, we have just leaned them left to right when we over-filled the bator. You can even set them a little more on their sides, but it didn't change the hatch rate, so we only did that for one hatch. We have also used a block and elevated each end alternately. This works ok, but some of the cartons weren't as rigid as others. (Ended up with more of a curved ramp.) Both methods worked well for us, though.
If you have room, what seems easiest is to use the smaller dozen carton instead of the larger 18 ones. Then you can put a length of cardboard tube or pvc under the carton and easily rock the whole thing side to side. I currently have an 18 on the dowel for the paper towel holder. It's fine, but you have to move the dowel (to between the middle and upper end) each time you want to rock the eggs. I think it would be simpler with a dozen as you'd not need to maneuver the rod.
One thing I should have said about the plastic canvas set up. We had the eggs all together until day 18. I let the girls cut out the shapes and bottoms of the cartons ahead of time so the switch was smoother. Removed the carton they were in, put the plastic in place, dropped the 'tetris' shapes in (no straight ones though, you have to have at least 3 in a v or they tip), then candled and set the eggs in their 'cages'. If your house is cold you may want to put a towel over the eggs while they wait to be put back in. We don't have AC, so all we did was close the windows.