Your plan looks good. Pretty average from what I've seen, although of course every LO is different. I would prob look more towards the 2 hr nap rather than 1.5hr and only reduce further if you really see a need for it.
What I've found most useful is set nap and set BT. Obviously they are not set if you are the process of tweaking the routine but I would really try to stick with something and let it settle in rather than changing BT every day based on nap length and A times. A times for younger babies are super to go by, but at this toddler age I think they like the predictability of knowing when they are going to be put down to sleep.
Our 5am WUs started with illness, led to OT because of the short nights, and then I think the OT added to the EW. But eventually ended up UT, I can see the difference in him even though I tend to be slow on the uptake and don't act quickly enough to prevent problems! I'm almost positive there is a milk or postal train going by here in the night too and the noise waking him.
I went out on a limb recently and used an illness disturbed night (lots of long NWs) followed by a later morning WU to kick start a new routine. Rather than:
WU 5-5.30am
S 12.30 - 2.15/2.30
BT 7.00 (had started to UT refuse and S was coming 7.20-8.00)
After his awful night he crashed until 7.30 so I used that to my advantage but it is still a flexible process whilst he is ill.
Looks like we are on our way to
WU 6.15 - 6.30
S 12.30 - 2.30
BT 8.00
or at least trying it. Like you I'd like to see a longer night but a happy PD at BT and a decent amount of overall sleep in 24hrs so he is rested, energetic, happy, those are the important things. Seeing him groggy or grouchy in the afternoon is unpleasant and UT BT refusal struggles drains me of every ounce of energy I have. It just does nothing for my mood at all!