For my LO and his consistently short naps and tendency to get overtired, what I try to do is base his next nap on his wake time. It gets a little wonky with the feeds, since he could easily do four hours between feeds. Basically, I try and mesh things so that he goes 4 hours between feeds and has 2 hours of A time between each nap. It's kind of a crazy EASAEASAEAS So his day might look something like this:
7 up for the day, E
7:15 A
9 S (45 min)
9:45 A
11 E
11:15 A
11:45 S (45 min)
12:30 A
2:30 S (45 min)
3:15 E
3:30 A
5:15 S (though sometimes he skips this nap entirely)
6 A (bath around 6:30-6:45)
7 (or so) E then 15 min of bedtime routine
7:30 bed
It's not really EASY, but it applies some of the same principles. I found that I have to be a stickler about 2 hours of awake time, otherwise he will scream and fight and cry and refuse to nap entirely, just because. Recently, he's been extending a nap and droppign that 4th catnap, so that's been nice. I hope this made some sense and helps a little.