This is the first time that I remember seeing a more concentration of RV rentals on the highway in the Fairbanks area this summer than any other time, like a 1 to 3 ratio of RV's of Great Alaskan or Cruise America.
So it tells me one of two things :
1)- It's cost effective to rent one - or -
2)- Vacationers just do not have the extra time needed to travel from the states to Alaska by road.
My guess is 2) since there seems to be quite a demand from all the rental RV's I seen on the road upon a daily basis this summer.