I said your chiropractor is stupid for saying deadlift and squats are leg day.You told me that I was stupid for saying that squats were a leg exercise. You also told me that squats were the best hip flexor exercise. Anyway lets put your incredible statements aside for now and discuss your question.
The bench press properly performed includes muscle recruitment of the hip flexors and legs. Is the bench press leg day?
DOMS is primarily caused by eccentric contraction. The only thing that protects you against DOMS is doing the activity more than once. If you are experiencing recurring pain from skim boarding you are likely feeling a minor recurring injury, like inflammation or joint pain due to incredible weakness.
Doing bodyweight exercises runs it's course of usefulness fairly quickly. You adapt to the stress and unless you are continually gaining weight the adaptations cease.