Canyon CG in Yellowstone any fudge room in length

I am facing a similar issue, heading to Yellowstone in about a month, I booked 30 ft rv spaces in 3 of the campgrounds 6 months ago for my 29'5" long motorhome, and now I have added a rear spare tire mount which extends my overall length out to 31 ft. I plan to show up and hope for the best, worst case I will unmount the spare tire if they get out a measuring tape.