My first thought for something actually doable would be a group of compressed gas cannisters with highly reflective balloons attached to them. Very simple mech

My first thought for something actually doable would be a group of compressed gas cannisters with highly reflective balloons attached to them. Very simple mechanics, all you need is a strong valve on a timer, so it can be made to survive the impact with the ground. Once they're inflated, they would rise to relatively high up, so they can be carried off by winds. Because of the high reflectivity, we would be able to track them from orbiting imaging satellites and probably even from earth, teaching us more about wind speeds and flows on Mars. One thing I'm not sure about is if this could meet the weight/space requirements.