Cal, my DW and I did a similar trip 3 years ago, Vancouver B.C. to Halifax N.S. and logged 13,500 miles. Crossing west to east mostly in Canada and returning through the northern USA. We were on the road 9 weeks.
The advice I give anyone planning a similar trip is; look at your planned route and mark off areas close to home that you have been to before, or are likely to see on a shorter trip at a later date, and go through them quickly. Get across the country to the area you want to see, this trip, and are likely not going to get to again, and spend the majority of your time there.
On a side note , on the east coast , many RV parks start closing for the winter after mid Sept. something we were not expecting, being west coast natives . Even in the northern plains , in early Oct. we were in parks that were in the process of shutting down for the winter.
JMHO. From Ca. cross the country on a northern route and be prepared to return across the south to avoid cold weather.