If you want to improve your sidestroke, go to the experts: the Navy Seals.
This is the stroke they teach for both stealth swimming and long-haul swimming. There’s no “arm in the apple basket” lingo here; the arm movements are “pulls,” and it turns out there’s two of them, a primary and a secondary. Who knew?
There’s even a “sprint” sidestroke. The instructor in this video recommends using the regular stroke for the first 400 meters of the Seals’ swim test, then switching to the sprint version for the last 100 meters. (Same distance as the swim segment in the Fox Island triathlon. How cool is that?)
Much as I worship this instructor — I’ve watched this at least three times now — I am NOT gonna put my face in the water and attempt to breathe, dude! Open-air breathing is what drew me to the sidestroke in the first place…