Safety first, last and always!

If you're wearing a dress, I see nothing wrong with wearing knee-pads underneath to protect yourself.

Have you thought of talking to someone in the marshall arts? I mention this because years ago we had a karate instructure come in and help us with some flips and falls for a show.  I can't remember if he had training in stage fighting, but I remember him as being very helpful. Just a thought.

Linda

Good piont Linda.
I learnt to break fall in my youth, through a marshal art. Which stood me in good stead, when doing prat falls on stage. When falling down stairs & being thrown in an irish whip & the like.
Useing your arms & hands to flat hit the deck first, reducing the force of the body weight.
In falls most injuries are caused by trying to stop falling, by tentioning up. This is why drunks never seem to hurt them self, even in the worst accidents.
I have fallen a number of times, when for what ever reason. a talescope has toppled over. Relaxing & going with the  equipment by remaining in the  hiosts basket, rather than trying to jump clear nothing happened, except for the sudden stop. Be aware of your body parts possition & go with the flow of the fall.
I would be more worried about falling on my transum & damaging my coccyx, then falling forward & scraping the knees.
The things you have to watch out for is jiont damage with elbow, hips & the like. Going down stairs is easy because there are structures to break & dampen the forward motion of the fall, but plan it out & rehearse it. Cushion or pad protruding objects & clear away props they will cause harm - then 'idiot check' the flight path, before you take the fall.