I do agree with a good inspection of the chassis by a qualified shop. We did Alaska in our coach in 2014. Due to weather, we did not do the Top of The World run (We visited Chicken after spending a few days in Tok. Took our Toad and drove the opposite direction from the normal RV traffic, until we reached about half way on the Top of The World 'trek', then returned to Chicken.).
As mentioned, lots of opportunities for rougher roads, and construction is a constant norm - just different locations each year, while on this trip. That being said, we did not find the trip too stressful for a chassis. I've had more damage on California highways, then I ever had on our trip to Alaska
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Once you get the battery compartment cleaned up, and rust proofed and painted again. A switch to AGM's will keep it looking like that for a much longer period of time then if you put wet cells back in. Even our Chassis Battery is now AGM, though I will share that the CAT Maintenance Free Wet Cell, did very little outgassing in our 5 or so years of usage. Drank some water, but much less then I had anticipated.
Good luck on the inspection, hope it turns out to be the coach for you
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Smitty