We've taken 87/260 with our 40' motorhome. The first part is a piece of cake. You'll have a long downhill (6% for 9 miles) on 260 to I-17 but very doable if braking correctly. Get into lower gear before going down, not in the midst. It's all a beautiful drive. If you take I-17 you'll also have a long downhill - 6% for 14 miles) to Camp Verde. We've also done this. We prefer secondary roads though.
Are you staying at Dead Horse Ranch State Park in Cottonwood? It's very nice and an easy drive to tour Sedona, Jerome and even Prescott but don't take the RV that was to Jerome - you won't like it but definitely take your towed there.
Have a good trip!
