Oh my goodness
You see Hun, hand on heart this is the type of situation where I would often crumble and give DS an early nap after such an awful night. BUT, having been where you have been and having said all we have said, who knows if it would pay off, or if he would refuse nap anyway, or take an earlier SHORT nap, in which case you are in 'no man's land' stuck with a LO who is exhausted and has hours and hours to bed time, then would more than likely need to shoot for a cat nap in the afternoon.
WRT BT, and the length of the day, you are right, he would need to tack on lots of sleep in order to really shorten his day, and allow him an early BT.
For all we give our best advise based on our own experience and the experience of others, I think it is important to remember that you are his Mammy, and you know him better than anyone Sweetie. If you feel it is right, then observe him and go with your 'Mother's Instinct' today, nap him when you think he is ready, and see where it gets you. If it doesn't work out then you have confirmed the current plan is as good as it's going to get. If it does work out, best case scenario he pulls a nice long nap and you get to a decent BT after it, then all the better.
I hope this doesn't throw you into a tail spin, I just would hate to have you feel like you are not in control. It is always your call ultimately as to what you think is best for him.
Many ((HUGS))
x.