Hi Consmummy,
2-1 transition is very tough, even for my DD who is going through it right now. Like yours, my daughter has very early morning wakings which makes it really hard for a 1 nap day even with the early BT. Actually, we are going through very bad OT buildup right now which was a result of my giving her too many 1 nap days. What I've noticed is that you may find the first few one nap days to be great where they will have nice long naps but then gradually they start to short nap as OT builds up more and more. This is what happens with mine. I think if he fights going down in the morning, maybe push morning A a bit later and then, like you did, give him a shorter a.m. nap so that he'll be tired enough in the afternoon. If he's able to have such a great afternoon nap, it sounds like you are doing well.
I'm definitely envious of such a great p.m. nap. Right now I'm struggling to get my daughter to go down at all!
Good luck!
Christine