With all the camp sites available inside YNP, why stay outside the park? There are over 1700+ sites inside that are available by reservation and 450+ more that are first come first serve.
West Yellowstone is no more than a tourist trap. Grizzly RV is a very nice park and a great place to stage prior to moving into YNP. For the most part, it is much more expensive to stay in West Yellowstone than inside YNP, the drive is longer each day, you miss out on the evening ranger led campfire programs and for the most part evening animal viewing. Not to say this couldn't be done, but one must then make the drive back out to West Yellowstone.
Sure, some vehicles are simply too big for the campgrounds inside, but most will fit. I've even see 43 foot MH's in Fishing Bridge where the limit is supposed to be 40.
Why travel all that distance and not experience the real YNP? Stay outside if you must, but by all means, at least make an attempt to stay inside. There is so much more to offer. Now if you need to go out for some groceries that are not available inside or see some of the tourist trap nonsense head for a day trip to West Yellowstone. Making that trip every day both in and out is a wast of time and money.
Keith