Short Morning Nap

Shelby
My baby is 7 months old today (😢) and is falling asleep on his own in his crib. His morning nap is 2 hours after wake up, but lately has been very short, 30 minutes usually (40 minutes tops). 
He wakes up happy and usually takes a longer afternoon nap, then another cat nap around 3/4. Sometimes with this short morning nap, though, that leads us to 4 naps a day! 
Any recommendations for extending this morning nap a bit? He is prone to overtiredness, so extending his wake time past 2.15 hours isn't really an option. He goes down easy at the 2 hour mark. Thoughts?!Â