I even did 2 naps with my 21 mo (currently teething canines) old yesterday!! We don't do them very often, but when she's headed into that dreaded teething OT and has a short night, it's the only thing that gets her through the day.
I'd say you're right on with your assessment, Sharon. The 2-1 is really a matter of being flexible with what they need to get through it. If she'll still do the 2 naps, I'd go with it, and then go right back to 1 as the OT eases.
One other thing, I'd watch her really closely after the 20 min nap. She may be ready to go back down at 12:30, or could last until 1 pm. It's different for all kids, but my DD still hovers around 3 hr A after the 20 min nap.