2 Part Technique - The protocol for attacking the neck while laying with Seatbelt Control on the under-side is as follows: (1) Gang-up on his defense by using 1on1 Wrist Control and trapping his other arm under your top hook with the Arm Trap from Back. (2) If you encounter difficulty getting your wrist underneath his chin, switch hands for wrist control and pry back his head like a Pez Dispenser to open up the neck for the choke. And (3), if one hand isn't enough to pull his head back, release his wrist and dedicate two hands to pull on his forehead. Since you let go of his wrist, he will have an arm to defend his exposed neck in two ways; if (a) he protects the bottom of his neck, cut across the front of his throat and crush with the Straight Short Choke. If (b) he hides his jawline, then punch through the gap in his arm from underneath with a contoured fist, and finish again with this same Rear Naked variant.