@Martin Joe &
@Kozushi - I find ample lower back work from the pistols, bridges, arch-ups, drinking birds...etc. Try them in timed holds and reps...etc. I typically found more pain and less mobility from deadlifts and I currently believe my strength levels are fairly similar despite not touching weights for a few years. Kettlebells gave me the same problems despite endlessly attempting to fix my form...etc. I own Get Strong and many other calisthenics books, I landed on the Fighter Pull-Up Program for my basis of my training.
@Will Moore - Time under tension is a great thing. It can make 20 push-ups feel like 100. The greatest thing, is that when the intensity increases, the time under tension does not need to be as long. So maybe a set up normal push-ups takes 60s of time-under-tension, a set of one-arm push-ups may only need 15s (meaning muscle building / activation is the same). This is backed by actual clinical studies and is encouraging for those of us who do not want to spend hours and hours working out.