Hey Eloise, was just thinking about you and wondering how you were getting on
I can totally sympathise with not being able to get him to take an arvo nap....J is exactly the same! No matter what time we try, even 5pm
But then we have a normal wakeup time, so not a problem thankfully!
If it were me, I would at least try a quick 10/15/20min nap at 5pm to see what happens. You can always stop doing it if it doesnt work. Yes, he probably will be grumpy, but if it fixes the issue its worth a go? Try it for at least 3 days to see if it has an effect. In theory it should help you get a decent bedtime (i.e 7pm), so that morning wakeup is pushed back. I would give him his tea (maybe a little earlier), then short nap, bath, bf & bed.
Can't hurt to try it, what do you think?