Make sure you stretch tall before and after L sit practice- it helps keep the cramps away. I use the fingers locked on my toes and arch backwatds stretch and no longer get the cramps…
L Sit progression is tough-
try all the varieties
Tuck sit on the rings, from the floor and from the paralettes.
Toes to the bar and Knees to elbows will support your progress.
When we have kids who can tuck sit, but not yet L sit we will get them in an L sit position and hold their feet for a short count and then let go, lessening support as they progress.