Stick to your side of the bed. If the bed is small, consider using a body pillow or a rolled-up blanket as a physical divider.
It’s better to politely state that you’re a "restless sleeper" and would prefer the floor than to spend a night in discomfort. Share Bed With Stepmom BEST
Explore using an air mattress, a couch, or even booking a nearby hotel if space allows. Stick to your side of the bed