Hey Theo, you are not the only guy running a large frame AR in 6.5 Creedmoor. Here is a pic of my Mega Arms monolithic in 6.5 CM.....
I haven't shot it a ton yet but I know that all of the ammo I have tried so far fits inside the Pmags I have and I've tried factory 120 gr Amax, 140 gr Amax, 130 gr Berger hybrids, and even the 142 SMK. I will try to get a max COAL that will fit but I do know that all of the ammo I have for my bolt gun 6.5 CM will work.
My barrel is a 24" 1-8 twist SS Brux.....but I'm sure that your 1-9 twist will stabilize factory Hornady 140 gr Amax's.
Post some pics of your LMT when you get a chance, I'd like to see it.