If second nap gets cut short I don't think you have any choice but to try for a CN
. Other than super-early bedtime but that's not sensible 5 days a week as it will become 'normal' bedtime. Realistically if her second nap is going to be disturbed every day or she will refuse a third nap, I would deliberately cut short your first nap and aim for a longer restful sleep at midday-ish until you need to leave for the school run. That should see her through the afternoon a bit better than having the long sleep first, and you may also need to pull BT in a touch sooner.
You could start by chopping 15 mins off the morning nap, and bringing the second one 15-30 mins earlier. And do that progressively until you end up with a short catnap in the morning and a longer lunchtime sleep. Something like:
9.45-11 and 2pm
9.45-10.45 and 1.30pm
9.45-10.30 and 1pm
9.45-10.15 and 12.30pm for 2h, bedtime 6/6.30 depending on how she is managing
Obviously those exact times probably won't work, you'd have to follow cues, but could that general idea help you in any way?