In #3, I'd say you could try experimenting with a different setup on that backhand so that your shoulder turn away from the ball gives you a little more room to swing to contact (try turning your shoulders a little further sideways). I'm only looking at one example in that clip, but the upper half of your body may be muscling the stroke a little more than you want over the long haul.
I get more of the same impression after looking at #2. Your shoulders and hips remain slightly open through your backswing - maybe a little more Wawrinka than Federer? See how that stroke works if you can set up a bit more sideways. There might be a more complete kinetic chain to work with, but your best employment of the one-hander could be from right where it is now.