Rad. Thanks for the help gents. All super relevant.
I gave up on printing a big image through 420 mesh and made something 7" wide. That helped. Normal pressure was fine, though stabby pressure was essential. Dead smooth stock is understatement. I had trouble printing on the smooth side of Rives BFK. Never though I'd want to calendar my own paper, but there it is.
Printing small images through 420 mesh by hand was actually kind of nice. Dot gain was controllable, and a 105 lpi halftone caught nearly the full range.
Not looking forward to going back to my waterbased shop. UV is so good...