Scrub Island has a loop road - used to be dirt and I assume it still is - pretty flat and I’d bet it’s a mile or two at best - I think that would work out really well for you on day 1 of your trip….I’ll trey and see how long that loop road is but it’s flat and has great views…

Anegada is probably the best spot overall.

You could also find a nice wide beach and run back and forth….Josiah’s on Tortola comes to mind.