We did it... 2 naps and 3,5h of total day sleep. More than on 3 naps btw and blocked in two nice long naps. 11,5h of night sleep. No meltdown however tired for every single nap and tired for bedtime. Two brief NWs with crying but I just shhhhh and he got back to sleep. Don't even know if I was needed as the intervention lasted 15sec. Probably OT but he was waking the same when on 3 naps, so whatever. I know that I am keeping him awake for a loooong time but he settles like a dream for naps, sleeps soundly 1,5h-2h and is in a good mood in the afternoon what makes me believe that's a right direction.
Still:( feel a bit guilty for tiring him out so much but hope it will be better for him.