Yep sitting trot is always easiest to learn any sideways and lateral movements from, as you can feel so much more of what is happening than if you rise it.
But yep, if you struggle to sit trot then it makes it tricky ;)
Try at walk first, trot is easier for the horse, but walk is easier for the rider as it happens much slower!
If your sitting trot involves you slapping around like a bag of potatoes on the back of a wagon going down a rocky road, then I'd rise it first. You don't want to be blocking the horse's back by slamming into it in sit trot.