We also would consider a smaller RV on our next trip but we saw all sorts of RVs up that way from the very smallest to huge motor homes. We had a large 5th wheel and we stayed mostly in some sort of campground because we had to have a place to leave the RV when we went site seeing and we would not leave it in a gravel put or turnout unattended. We did not travel every day as there were some interesting things to see on the trip up. And that day after say travel is so tiring. An example, we stayed in Pioneer RV Park in Whitehorse but we elected to dry damp in their upper section. The water fill and dump station were up there and so was some RV storage. For $11 it was great for us. The FHU sites were crammed together and there was quite a bit of road noise that we did not hear because we were up on the hill. While staying up there, we woke to see a couple of rather large foxes frolicking by our RV. The smaller the RV, the more versatile you will be. We could not drag our RV to the local grocery store or restaurant.
We loved the Stan Stephens Columbia Glacier Tour in Valdez. Have some sort of nylon rain jacket to wear because the closer you get to the glacier, it gets frigid. Gloves and something for your ears would also be good. We stayed out on deck almost the entire trip and we saw some amazing sea life.
Driving to Alaska does make you feel like a pioneer. It is so worth it!