Taking a long bus ride. Don't have access to compression stockings. Any tips?

I am taking a bus trip halfway across the US. I can't afford a pair of compression stockings and my insurance doesn't cover them because they aren't medically necessary (because a $60 pair of stockings that could prevent a clot and possibly thousands of dollars in hospital bills isn't medically necessary). I am planning on getting off the bus during longer stops and doing a little walking.

Is there anything else I can do to prevent possible dvt? I'm on lifelong warfarin therapy and my inr is therapeutic right now but I'm still terrified of getting another.

Thanks so much.