Sorry I've just read all of this now.
So, I would just adjust the light schedule to be off during the hottest part of the day.
Don't worry too much about the high temps, especially now. It might be a problem in flower, but even then, I've had good yields with a hot summer and an HPS hitting well over 30 plenty of days, it's not the end of the world and you've trained them hard, they won't end up being too close to the bulb.
I wouldn't bother with the AC. It sounds expensive and you'd be better off saving your money and getting a decent LED down the line, which will also bring your electric bill down whilst giving off half the heat.
The plants won't be huge, you've trained them pretty hard for autos. I
knoooooow there's plenty of people here that do that, but they're not getting a bigger yields. Autos just don't really work like that. Best off to train a bit just to improve exposure and level them out a bit. Topping and mainlining might be more interesting, but I've never once seen it improve a yield, often the opposite and usually it makes no difference. It's great if you're limited for vertical space but otherwise I don't see the point, all it really does is ensure small plants (i should stress that doesn't mean small yields though!)
Every plant I've trained hard, I've pulled 3-4oz from, every plant I've pretty much left be, I've pulled 4-8oz from.
Leaves look nice and green and the plants look pretty healthy. I know they're a little on the small side, but they have some time to stretch and the strain doesn't get that big either.
I wouldn't worry too much about the feed either, it's probably fine you just need to be doing it every day rather than every other day. Don't let em dry out and they'll be fine.
There's no where near as much to correct than it sounds like you think there is. They're happy looking plants but next time I'd recommend easing off on the training a bit if you want a more satisfying grow.
RH and temps look fine too! You're all good!