How about a long nap 1, then a CN before school run, then a long nap 3? I did this, not for school run but another reason, and it was fine. Eventually, much further on it was nap 2 I dropped (the CN) rather than nap 3. Hope that makes sense, nap 3 was a longer nap not a CN.
So you'd extend first A time to where it needs to be to get a good sleep, you can let that nap go longer probably, 2hr, then second A time you keep a bit shorter if he will be willing to go down a little earlier (not all LOs will of course, he may need a full A time to accept a nap), as it will be a CN of around 40 min you can begin as late as 2pm and still be up in time for school PU. The third A time might be a bit shorter than is full A due to it coming after a CN rather than a long nap, so maybe 4.40/50 ish and he might want a longer nap.
Overall the amount of day sleep doesn't alter in the first instance, just the time of the naps, so BT could logically stay in the same place, but if there is BT resistance I'd probably be willing to move BT a little later for a while or begin to reduce nap 3 to maintain BT.
A very rough guide (which gets messy as the day goes on because it really depends on if he will take a shorter A time anywhere in the day before or after a CN)
WU 7
A 2hr 30
S 9.30 - 11.30
A 2hr (or up to 2hr 30)
S 1.30 (or as late as 2pm) CN 40/45 min
A 2hr (or up to 2hr 30)
S 4.10/50 - 5.30/6.00 (a long nap will fit in here)
A 1hr 30 (short but it's what you are doing now roughly)
BT 7 or a bit later
and a very rough guide for when A increases to more like 3hr
WU 7
A 3
S 10 - 11.30/12 (if he will sleep longer here it helps to drop CN and move nap to after school run)
A 2.5 (when this can increase to 3hr you drop CN and do the long nap after the school run)
S 2pm CN 40 min
A 2.5
S 5.10-5.50 (this one moves earlier when CN is dropped)
A 2
BT 7.50/8 (late but it will go earlier again after CN is dropped, back to around 7pm)
What do you think?