Would a submentoplasty be an easier way to remove extra skin/fat underneath my chin/jawline?

I am 23 and have always been very thin (underweight). I have a decent bite but was told I would be a good candidate for a sliding genioplasty, where my chin would be moved 5 mm forward and 5 mm downward. However, what bothers me the most is the extra skin/fat underneath my chin and jawline. I had a tiny bit of filler and it didn't really help. Would a submentoplasty be an easier way to remove this, as I was told a regular liposuction probably wouldn't help me? Or is a sliding genioplasty best?