That's a good point, thanks!
I've gotten alot of good ideas from this thread, y'all are awesome. I'm going to shim with a deck of cards, I got some stiff 30 year old E&E playing cards with edible plants and tiny ass print that I'll never be able to read without a microscope, so glad I hung onto that. I'll do that while I look at the reticle over a plumbline at distance.
There's 2 clamps, should I obsess over the gaps on the sides of the clamps, or is a little incongruence ok?