The width of prefab laminate countertops can be cut to any size. There are matching strips available that are applied to the (raw) sides.
I would have the contractor cut off the existing backsplash, use a leftover piece that was cut from the width to make a backsplash. You can again use the strips to finish the raw edges on the backsplash.
Of course, a custom top can be made. If your budget allows, get a price on that. All the big box hardware stores make custom countertops.

It will be in a gently used bathroom. Is there much concern for water damage? I am hoping that its a matter of how well the contractor drills for the fixtures and mounts as well as putting the side piece. On. For this cheap of an option it seems like its worth the water risk (if there is a risk) What do you think? Is there much risk to use laminate in a bathroom as compared to a kitchen?

Your contractor should easily be able to make you a top with laminate that you pick out, to fit exactly the space. I have done this in my laundry room and bar, and it's very affordable. Just pick out your laminate sample from the hundreds at the big box store and give him the brand and number.