You'll see all different sorts of RVs in Alaska. Truck campers seem to be especially popular, and I can well understand the practicality of them there. Depending where you want to go, relativelyy small ones may be a little more practical. A 26' trailer shouldn't pose many particular problems, generally speaking. Of course, any setup has its advantages and disadvantages and limitations; there are a great many areas in Alaska, vast expanses indeed, that cannot be reached by road at all.
If you're interested in traveling the Dalton highway, I would not suggest going with a brand-new RV. It's a rather grueling, sometimes rough trip for the vehicle. It's also one of the most beautiful roads I've ever been on, particularly in the vicinity of Atigun pass (but far from exclusively in that area).
IMHO a towed vehicle with a motorhome is less of a necessity in Alaska than in many other areas. The only areas where RV parking is much of an issue are areas where there's public transit available.
