I have not read the entire thread, but what happens if you push naptime back to noon or later? Will he nap longer? If not, at least you have a shot of pushing back BT??? Not sure, just a thought.
My DD is similar in age to your LO and due to daycare, has to nap around 12:30 regardless of WU time. She is getting better with WU (was a chronic EW 5/5:30 until switch to 1 nap). Even now, her usual WU time is between 6 and 6:30 - from time to time we do get pre 6 AM wakeups. I cringe on those days, but because of daycare, she has to plow through until 12:30. On those days, she'll usually nap for about 2.5 hours (average is 1.5-2). It's hard for us to move BT earlier than 7:30 (7:45 is usual) due to work schedules and an older DS in the mix.
Looks like he's getting 11+ hours of NT sleep - which is pretty good in my opinion. I started a thread about LO sleeping 12 hour nights, which is ideal, but doesn't seem to be the norm. My son was a fantastic NT sleeper and never managed 12 hours, more like 11. HUGS!!!
Edited to add, my DD does get a bit fussy at the end of the day when I pick her up at daycare. But she is usually better after a small snack, some rough housing with big brother, and then dinner.
