Well i must say that living here Jackson Hole and having camped every where in Yellowstone I would have to say that The Bears here I not going to rip into your Van for food. The main reason of course is that some yo yo is going to leave his in a tent and not in a bear box Most camp site here have bear boxes for people to use.
The biggest problem is this year several bears have had very large litters (4 cubs) thats almost unheard of.
Dont get me wrong there alot of Bears here and they are really active this year with the snow being so deep up high. Your food will be safe in your fridge-dont dump your dirty water in your campsite and you will be fine.
"Carry Bear Spray" if you have never used it buy one just to test so you know what to expect.
All so ask the rangers if there have been any bears around they will tell you they know them well they are all taged and numbered.
One more thing
I hate bears they scare the poop out of me. It is the one fight im pretty sure I can win.
Have Fun
Ron