He's a little tinker, isn't he?
I'd be tempted just to go for it, maybe allowing him a nap every second day or so, then every third, every fourth etc until he can cope with no nap at all.
Can you set things up so you do something quiet after lunch instead of offering the nap? We cuddled on the sofa in front of a DVD and sometimes he's drop off, sometimes not. He'd had a rest either way, and it's still something we do today to catch up after a busy week.