Hi
At 8mo most LOs are well into 2 naps so your shorter naps and EW is likely from an early-ish first nap and late CN.
I think I'd try pushing A times to around 3.5hrs so starting that first nap later and see if you get a longer one, then A time 3-3.5hrs again again before 2nd nap and see if you can get to 2 naps of around 1.5-2hrs, no 3rd CN.