You could superset 5 dips with the main lift and the chins, or do push ups. the dips aren't required but I recommend them. By the end of BTM I was able to do 165 bw dips in 12 sets.
Since you have 14-16 main sets (including the squat warm up sets and maybe a set or two of press warmups) try this:
Continue until squats are done then
Finish the workout with face pulls or pull aparts.
I can tell you that BTM is a lot of work, both physically and mentally. With warming up, agile 8, jumps/throws and the lifting, I was in the weight room for damn near 2 hours, three days a week. Not to mention, I gained 15 pounds in 6 weeks eating the way it is written, and I'm 39 years old so gaining/losing weight isn't that easy at my age. At the end I was able to press 135 for 17 reps and squat 405 for an easy 5, and could have certainly gotten more but was simply testing my TM.