https://www.youtube.com/watch?v=9q6d-5_px2Iprob the most helpful tip vid I've seen on it. It helped me get them more consistent for sure and I skate a 8.38 to 8.5. My most helpful takeaway is when you scoop your back foot, scoop it back and towards the front foot ever so slightly. Like a diagonal back and forward. And remember to spread the back foot back out immediately after scoop to avoid having your feet super close together when landing.
If getting the big board around is your problem and you don't want to downsize, my main tip is to make sure you're kicking your tail smarter not necessarily harder. What I mean is I tended to flail the board with alot of energy before, but learned that if I focused on getting a clean scoop and really nail the sweet spot on the tail, it rotates no problem. Work on finding that sweet spot and you won't tire yourself out kicking it around. It's a big mental hurdle but it helped me alot.