For max reps at each station:
Mins 0-4 Tabata chest-to-bar pull-ups
Rest 1 minute
Mins 5-9 Tabata sit-ups
Rest 1 minute
Mins 10-14 Tabata good mornings 45/35
Rest 1 minute
Mins 15-19 Tabata back squats 45/35

The Tabata interval is 20 seconds of work followed by 10 seconds of rest for eight intervals.

Tips: As fatigue sets in, it will be difficult to perform several exercises in this Tabata workout unbroken for the full 20 seconds in each round. Modify the movements and loads so you can complete the first few rounds of each.