Hi, if you LO is only 10w and sleeping well at night I wouldn't worry about one longer and two short naps. It is early days and maybe a little bit too early for sleep training. Most babies at this age are not even sleeping through the night yet. I would wait a little bit and see in 1 month time.
If he can sleep more then one cycle in one nap (you said he gets one decent nap) and it doesn't seem too difficult to transition from one cycle to another, then maybe this is what he needs. My DD slept 4x45 for first 4 months and then it didn't get any better
, now is almost 9 month old and still struggling with naps and wakes up at 5am. I understand it is difficult with two, I have only one and struggling.