Conducting a study of Taikyoku applications aren't you?
Applications can be discovered similarly to Taikyoku Gedan. Think of preparatory motions in the chudan uke, and think of the transission and in-between movements.
For starters, the preparatory movement of any chudan uke can utilize the rear hand to deflect the punch and use the blocking hand to apply elbow lock/strike and arm bar, while stepping outside of opponent's attack such as in the opening movement.
In the beginning, after the first oi tsuki, you step around 180 degrees to your right, and execute the next chudan uke. This can be stepping to the outside of a kick, catching and trapping the leg with chudan, then step with the left tsuki while holding leg to take opponent down.
Have fun experimenting with this!