I'm not sure there's a good solution to this. I'm the opposite, I go to bed early and get up early, I've drifted that way because of insomnia more than anything, and I have exactly the same problem every year.

I did get a portable ACU about five years back too. I've done as much as I can with that, with ducting through the bedroom wall for the exhaust, and it's far from ideal. It's a lot louder than expected, and the flow of air seems to disrupt my sleep. Despite being one of the more decent ones from the time, I can't position the air outlet such that it doesn't bother me for some reason.

I'm already considering a split system, but don't know if this is just throwing good money after bad.

Anyway, enough moaning from me, and I do hope you manage through this difficult period. You are at least not alone, though I know that doesn't help at all.