Hiway 89 in Utah to skirt W. of SLC
 

My son is wanting to ride up 89 from AZ. He needs to miss heavy traffic from at least Spanish Fork to Grantsville. What routes do you suggest for early July? What about water for hydration - stops and distances? Is it legal to use the shoulder on I-17? What is your opinion of riding from Beaver to Delta on Highway 257 and taking the back roads 6 and 36 to Grantsville? He could take Highway 20 off of 89 above Panguitch to I-17 but would have to follow I-17 to Beaver and then veer NNW. Any suggested daily itinerary?
Thanks for advice.