Hi there!
When we did my shop (36x50), Dad mixed the material, then poured it out in "ribbons" over the area. I moved the material around with a floor squeegee, then rolled it out. An 18" wide roller frame made a big difference. When we did Dad's shop a couple ofyears earlier, we used standard 9" rollers and it was definitely more work.
Another thing I did this time that worked was to mark the floor into sections. We were mixing half kits at a time, so I marked the wall next to the floor off into sections with a felt marker, where each section was the area for a 1/2 kit. That made it pretty easy to know where that pour should cover, so we didn't get it too heavy or light in one place. It worked out really well -- no unexpected leftover, and no running out early.