Erik, you are currently 5 degrees warmer and 5% more humid than I am, so yeah, we are close, lol!
In using glass carriers, AN or otherwise, I have got Newton Rings every time with both TMX 100 and Acros 100. I did a 11x23 with a 6x12 Acros neg last night and got a small set of rings in the center, no good...:-(
Maybe I'm lucky or you are cursed as a last ditch effort if you can't eliminate the problem you can fluid mount the negs. I've done this to negatives that were in bad shape with scratches and dust I couldn't remove and it was a big improvement and it would eliminate your newtons rings I would think. I used kami fluid as well as naphtha for the fluid, Mylar on top and sealed with tape. The sandwich lasted all day and didn't dry out even with 1000 watts of hot halogen lights blazing on it
I went through a phase of experimenting with Denglas (no longer made) and Tru Vue AR, mostly for contact printing applications. I got them from a local high-end frame shop which, up to a point, was willing to cut pieces to size for me. I say up to a point, because it was apparent that they began to think of it as a nuisance after a while. Part of the problem was that it was sometimes difficult to find pieces that were sufficiently blemish-free for my purposes, and they understandably weren't willing to keep sorting and searching their stock of expensive, fragile museum glass for a purpose that was unrelated to their business.
That said, if you can get a clean piece of AR-coated glass in the size you need, I do think it's worth a try for a carrier bottom glass.
I am definitely going to continue to pursue the other glass types, I don't care what it costs at this point either, it is wrecking havoc on my production which is far more costly overall than the price of glass.
Like I said, 4x5 TMX and TMY is less of an issue at the moment because it stays oh-so flat in my glassless carrier. But in 120 that and Acros is another story.
Frankly I am surprised this does not come up more, I can't sell prints with damned newton rings on them....
"I'm the freak that shoots film. God bless the freaks!" ~ Mainecoonmaniac ~