Between the 40' max and "Please keep in mind that most campsites in Yellowstone will not accommodate oversize units. If you arrive at the campground/RV park with equipment different than that for which you have reserved, we will not be able to accommodate you" not sure I'd try and make your 45' into a 40'. Sometimes my 42 becomes a 40 but getting a 45 to do that is stretching it.:W I'd call and ask if they have a site big enough for a 45. They also want to know the total length of the MH plus the toad. Guess you could rent two sites and put the toad on the second one if staying there is that important.