Your questions are in areas of personal preferences that vary all over the place but a few of our Class B things:
On board bathroom. We have used ours for a shower once in 10 years and 130K miles. We find campground showers much easier. This is indeed a personal preference. We find a shower every other day suffices so we can dry camp in between.
Class B Storage. We have never had a problem in our LTV. We do travel pretty light as there is always Walmart. We use plastic boxes to fit into and better organize some of our storage areas.
We always swivel the passenger seat around that I use for non-TV activities and my wife uses the sofa in back for TV watching or whatever.
Campground occupied sign. Again, unlike a lot report, we have never had a problem in our travels. Most campgrounds and parks assign you a spot so it hasn't been an issue for us. We always leave our water hose at the site if we leave but that is not much of a deterrent. Never lost a water hose though. We don't "unpack" at a campsite such that we can't drive off in about 5 minutes and the same upon return.
We seldom reserve campsites more than a day or two ahead and usually don't at all as we don't want to be committed to a certain travel plan. Seldom has been a problem as a Class B can camp in any available campground site.
Levelers, we tried blocks first but prefer these. Not needed a lot but when they are they are a must have. They nestle together nicely for storage when the ramps are put in opposite directions. And you quickly learn how to stagger them if needed or use them both on one side or on opposite sides if necessary.
![](http://i.imgur.com/mc2feaEl.jpg)