I always liked the drive on 199, and used to live 7 miles west of Grants Pass, where 199 joins I5. I never was concerned with driving 199, and had a relaxing drive the last time I was on it, with a 30' motorhome towing a dune buggy.
But mountain driving never did un-nerve me, especially if you have the time. You probably don't want to top off the gas in California, or in Cave Junction, (will be a little less expensive than CA) wait to Grants Pass to top off with fuel.
If you are wondering what your RV weight is, outside of Grants Pass, there is a scale on the right had side of the road. It will widen up a lot just before the scale, and look on the right. There is a turn off to Wilderville just before the scale. Last time I was there, I drove the RV and buggy across it, got the weights for the front and rear axles, and buggy too. The scale weight portion is on most of the time. 2 miles east of the scale, the highway turns into 4 lanes, until you reach Grants Pass, so easy to pass then. If someone asks when you stop at the scale, tell them you wanted the cars to get past you, and saw the wide opening. Look at the scale readout as you pass by. They are actually checking the weight of the logging trucks, to estimate how many board feet of lumber they have on board. And of course looking for overweight trucks too. RV's don't normally have to stop at a scale, but it is a free way to check the RV weight, and make sure you are not exceeding your axle or tire limits.
Have fun camping! There are many great places to camp. Lake Selma is another. Or Schroder Park in Grants Pass, right on the Rouge River, you can see the jet boats go by on their way to Hellgate Canyon. Lots of fun.
Hellgate.comFred.