Ugh I tried that. I have ridden in many many saddles, they all bruise without tall boots. I've been riding english for 14 years. Even when I was in lessons and had a very solid lower leg, still bruised without tall boots.
I have to ride with barely my toes in the stirrups, been thrown to much I don't want to be caught. But with the aussie I tried putting my feet all the way in until the stirrup was stopped by my heel, no difference.
It sucks, I have to trail ride in breeches and tall boots lol. Seriously I have tried putting my legs in every position I can think of.