I don't yet have experience with a Sunseeker (coming in April!) but on other 30 foot class Cs on the E-450 chassis, I would typically get many, many miles on the brake pads.
I suspect that you likely have a lot of pad left, unless there is a problem with one of them dragging or you like to ride the brakes down mountains
But, the only way to know for sure is to pull the wheels and take a look.