When doing the carnie do you want to have your trapped leg further down their leg towards their ankle or tighter up against their knee?
ANd the kung fu knee on the ground is super important. Its the same for all shoulder attacks from your legs. (omaplata, carnie etc) If you watch MG's videos on his omaplata game, he throws a straight leg over as far as he can, I think he even pushes the opponent forward a wee bit to break their base a bit as well. and the knee is glued to the ground.
Maybe think about holding the wrist with one hand and the other one to control their rolling.