11.5 hr is a good night, but sometimes he does even longer. And especially since he's teething and you're just still moving to one nap, my gut doesn't say UT. But it hardly ever does, so I may not be helping.
I wonder if I just need to only do one nap days if he wakes after 6.30 - otherwise when he takes a short nap we are stumped!!!
TBH, that is what I did as if it was a short nap, it just seemed like forever until bedtime. 6:30 am was my cutoff. And since he seems to be handling the 2 nap days still, I would stick to that.