I wonder what a sanwu 3X input lens would do, I have unscrewed the output of a 3X and it diverges less than natural but still fills the output lens with that bar, but that's with a 3 element primary, I would like to use a G2 in the 10X but reduce it to 5X with a different input designed to work with the G2 as the G2 lets all the power through.
Now as you twist the focus on your 10X you can see the output lens sink in, with it zoomed out being it is a wider lens and sits further away where the beam would be wider it may work with the 3X input, but that's after a 3 element primary. I wonder if sauwu has any BE input lenses for sale loose?
We really need a redesigned input lens, likely a wider and longer expander in the end as well, although the G2 will expand faster and in shorter distance.
I wonder if you left your input lens out and fiddled with the adjustment of your G2 so that it's bar shaped output would fill the output lens of the 10X be when screwed all the way out what we would get?
We may can just take out the 10X input lens and tune the G2 to work with the output lens, or we may need a very low expansion rate input lens and a wider hole, I want to use it on a 6X corrected beam.
I might just make a mount and set my convex cyl lens so that it fills the expander output at fully extended, or less depending on how short you want a tight spot.
It's going to take some trial and error, an adjustable cyl mount like cdbeam777 makes would be good.