We've had the 43' Bus and tow up to Tortilla Flat but going beyond that with an RV rig other than a small B or TC is risky. Small narrow bridges have very low weight limits and some sections of the road are only one lane with cliffs that overhang the road. A pretty ride up to Tortilla Flat and good ice cream and burgers there. Also a Forest Service CG for tents and RV's. The run from there up to Roosevelt Dam has some state road restrictions but we've done it with the toad. Fishing in Canyon Lake for bass can be great when the water warms and the fish get up on the beds.