There is a $15 fee to use the dump station for non-registered guests and water is available.

The dump station and fresh water is available for anybody. I believe it is $15. We were there two weeks ago.

Yes, there is a dump and water fill at LHSP that is open to noncampers. But dont count on just being able to use the facilities at any time. We needed to dump tanks after BLM camping nearby and were told we would have to wait until after noon. So, since we were headed south, we dumped tanks at Cattail Cove SP

During normal times, they charge a fee to use the dump station. During busy times, especially on departure mornings, they sometimes deny access unless you are staying overnight. Yes, there is fresh water fill there. There is only one fill (on the wrong side of the road, at that) and two dump lanes, so it can get pretty backed up. It was not designed very well.

I really do not know for sure. I never asked them that question. However, I didn’t see anyone who weren’t staying using the dump station.

Yes, RVs outside of the ones staying there can use the dump station (with potable water) for $15. However, they aren't allowed to access the station until after check-out time (at which time it becomes very busy). If your schedule allows it, I would use it later in the afternoon.