Yeah.. this was one of trips I had on my bucket list before I had my spinal injury a few years ago... but, I'd only intended on taking the RV as far as Fairbanks, and then riding the motorcycle up the Dalton to Prudhoe. As such, I did quite a bit of research on routes & options.
Here are my thoughts... pick & choose what you will from them.
1) Weather: Depending on how it goes next year, I feel your intended route via the Dakotas & Wyoming/Montana may be a bit ambitious that soon. Most of the passes were still closed around here in mid-May this year.. and many were still closed right into the fist week of June. But, as always, weather is unpredictable... so who knows what'll happen next year.
2) My intended route was to travel the west coast one way, and along the ALCAN the other... I just wasn't sure which one I'd take going north, and which I'd take on the return. The ALCAN route would be the one requiring less logistical planning, but would be the more remote.... while the coastal run would require occasional ferry-hopping, but whose locales would have more services available if needed.
3) I'd mentioned that I'd planned on taking the rig only as far as Fairbanks for one simple reason: there are virtually NO mechanical services available north of Fairbanks should any issues arise. And even for the very few that are, if a critical part is needed, one could be stuck there for weeks waiting on it to arrive.
4) Group travel vs. Going it Alone: This is only something you can decide. Going alone certainly gives you more options... but traveling in the group not only provides a measure of physical security in a remote environment, but the availability of physical help & advise if needed.
When I was considering going in 2015... I was planning the trip with a bunch of folks from the Facebook group called "Motorcycling RVers". About 25 of us were initially interested, and began throwing out ideas & desires of travel for the following year... but it became apparent early on that there was going to be very little agreement between us on various issues. I think eventually 5 or 6 did make the trek, but I lost interest and never followed up.
My biggest concerns were twofold: first was a major mechanical breakdown, resulting in being stuck there for extended periods & completely blowing my budget. The second concern was that I'd have to plan on completely replacing just about every suspension component on the rig when I got back... as by everything I've ever heard or read states that those unforgiving roads just trash everything. How accurate those accounts are, I have no idea.... but in the end, I decided it just wasn't worth it at the time.
So that's about all I've got. Personally, I'd love to go some day... but I'm not sure I'd go alone. I'd feel much more comfortable with a small group for the reasons listed.