AGC wrote:
... Can we get from Fishing Bridge to Grizzly through park loop roads with MH? How much time should we allow for travel? and what roads are safest?...
As said, yes you can travel all the major park roads in a MH. Some of the scenic loops and access roads are closed to large vehicles. Here is an
interactive map that shows the distances of the various road segments.
This webpage shows the status and condition of the roads within the park. The shorter route from Fishing Bridge Campground to West Yellowstone is a little over 56 miles. With the 45MPH speed limit, animal jams and slow traffic it can take a couple of hours.
In my opinion, the road between Tower and Canyon over Dunraven Pass is the least RV friendly, but is still very doable and many RVs travel it every day that it is open. It is a very scenic drive and if you are not in an RV, you can drive the gravel Chittenden road up to a parking lot from which you can hike to the fire lookout tower on Mount Wasburn.