I have seen some nasty stuff happen to people at 10 mph when the bike slid out on sand. Shorts and flip flops (down the shore).
If I was you, I would buy a bicycle.
I used to ride my Triumph to work every day till I got enough tickets and lost my licence, then I rode a bicycle 10 miles one way for 6 months, while working at the factory (actual WORK).
I was never in better shape.