Is a prestaflator necessary to use air compressor to set tubeless tire beads?

So I have these used Dura Ace WH-7850 tubeless compatible road wheels that I’m wanting to set up for tubeless. This is my 1st time at this and so far it has been rocky. I cleaned some old sealant out of the rim track for the tire bead with hot water and a scotchbrite pad.

Then I loosely mounted...