You're right the clones feet might be rooted to the ground/floor like a tree. I've never seen anything sprouted move from is original spot.
I guess in theory she could sprout disappear sprout disappear really fast to make it look like it's moving but that should be pretty hard to do.
It would also, be sliding it's feet along the ground and look rather strange. xD I think it's only uses would be for decoy or distraction purposes or for comedy reasons on the boat when bored.
Actually, she could make it walk as long as one foot is always on the ground/surface before the other lifts off. Still it would be hard.