Yes, here’s what I’m working on now: X & Y Skew Analysis
For the X axis you’ll want to extend the belt anchors by about a foot in either direction, so the frame should be around 8 x 12. I made some little extensions out of 2x4s and 3/4 ply. The accuracy is the worst about 2-3" from the edges so either avoid that or know that it might be more skewed there. If you can orient your cuts so they are moving toward the center or origin the accuracy should improve. Also, I’ve never run a horizontal setup, but since the machine isn’t fighting gravity it should be more accurate and you should also have less sled tilting.
I haven’t run any cuts after that last post and analysis, but those tips should help quite a bit. Hopefully we’ll be able to test some software changes soon that will fix these issues. Good luck!