I've heard a theory here that the body is uncomfortable with the launch because it doesn't like to die.

I've experienced the DMT RLS thing myself and posted about it.   I realize later the the thing those times had in common was that I was listening to Schpongle when it happened.  I think somehow my body just couldn't resist dancing. 

From the responses I got, I saw that the leg movements aren't a terribly uncommon thing with DMT.

I'm not sure how violently your legs are kicking, one theory on restless leg syndrome in general is that it can be a reaction to an over sedentary life.  I don't know your daily habits, but possibly try walking and more physical activity, if you're not getting enough that is.  That could possibly mitigate the leg thing somewwhat.