So, I'm having my kids do this and from the way I read the rules it *should* be legal - back spot counts as a base without question because it is below prep level so no need for an additional spotter, and according to Level 1 Stunts D:
During transitions, at least one base must remain in contact with the top person. Exception: Leap frogs and leap frog variations are not allowed in L1.
This isn't a leap frog/variation and it is a transition, not a release move since one "base" remains in contact. HOWEVER, I'm having the side bases keep their front hand in contact with the flyer up near her chest as she rotates into squish position because I figure that the safety judges are human and therefore cannot see through the flyer to verify that the back is, indeed, holding onto her ankles throughout the transition. It works, it doesn't take away anything visually from the stunt and it ensures that the safety judges can actually see a connection. Theoretically, it should not be needed... but again, safety judges usually do not have x-ray vision. If you could rotate the stunt so the connection with the back could be seen, you should be okay.
