You can carry the "Magic card" in the card box , leavening it in the box until your Ambitious Card performance is concluded. put all cards away with the "signed card " at the top of the deck. Drop the entire deck into the box. The burnt card doesn't need to match the Magic Card. Pressing the outside of the box in the corner will connect the two cards together. Begin the TNR magic.
Just my thought on how I could preform this combination into a smooth following ending to Ambitious Card magic.