I don’t think it would be wise to pray the Prayers at the Foot of the Altar, and to then turn away, with back to the Tabernacle, and face the flock to begin the Penitential Rite. It would seem reduntant to me, JMO of course.
As far as the Leonine Prayers, I’d love to see them added. I pray them anyway after every OF Mass I attend, and sometimes feel a need to also offer a prayer of reparation for the mundane chatter that erupts after Mass on Sunday. It’s sad how many of the flock jump into a social gathering mode a mere 10 minutes or less after receiving the Blessed Sacrament. It borders on sacrilege IMO. And to do so while others are still kneeling in prayer is rude. So yes, I’d like to see the Leonine Prayers added after the OF Mass, with the priest leading them.