[embodiment, movement] suggestions for hair styles?

As I mention, er, occasionally, I have fairly long hair that spends most of its time done up in a bog mummy braid.

This is great for most things -- gardening! cooking! cycling! washing up! -- but it turns out that it's not ideal for, specifically, Pilates, during the execution of which I want to be able to both lie on my back with my neck straight (rather than propped up on a substantial bun) and lie on my front while I wiggle my torso around, and spend time on my hands & knees, without my hair flapping around and annoying me.

Currently what I'm doing is braiding my hair as for bog mummy, spiralling and unspiralling (and arranging around me on the floor) as required for each exercise. I'm not holding out much hope that there are any better options (by which I think I basically mean "bog mummy, but on the top of my head not the back" or "shaped more like a bun that rests along my neck, but, like, without flopping from side to side when I'm not lying down")...

... but having described those hypotheticals I have at least one to try, heh, and if any of you immediately go "ooh, but how about--" then please do say!