Hi Stiltskin,
It's great to know that you feel better at sitting trot more than a rising trot, I really wonder

but you should feel like an expert then, sitting trot stability and staying in a good seat without bouncing looks too much hard to me, at least for now
How you keep intouch and stay still in seat without gripping? is it really possible?
I can't imagine staying in my seat during during a trot and not bouncing without gripping with m knees, even with a bareback, how you avoid bouncing without knees grip? still can't imagine it.
What's your technique or exercises that you tried to succeed in absorbing the movement?