Hello
First off at this age, you should be down to 2 naps more or less or at least working your way twds 2.
I would def extend ATs. That short CN in the morning I'm sure is inevitable but the next nap, merely 2hrs later - needs to be extended. I would aim for the nap to be closer to 12:00-12:15 and see if that helps extend that nap some.
It's tough with that short morning CN... is there a way you can prevent that nap? Sing or talk in the car or roll down the window, provide a safe toy to keep him occupied? I would try that and then nap as soon as you got home.
If NWs are more frequent and you know he's had tummy problems I would wait for that to pass and yes teething happens around this time as well :-/ lots of changes as I mentioned above
hugs