Wriggly baby - use of a bumper?

My daughter is 5 months old and wriggles constantly at night. Sometimes she gets in really awkward positions and will do a full 360 turn in a matter of minutes. Last night she was sounding particularly distressed so I went in to check on her and she had gotten her feet stuck between the bars of her cot, and there was a mark on her head from where she had bumped it on the bars. I know about the health risks of a bumper, hence me not having used one so far, but I don't know what to do to prevent further bumps and stuck limbs. Should I try one or continue to avoid them? Any advice?