IMO:)!
-Go for it! 45' as with a 40', just takes a bit more planning and does restrict area to some areas that just won't handle that large of a rig. Off the top of my head, I'd draw the lines into three groups for RV's/Trailers/5th's:
>25' and under, many options in the smaller parks
>25-35' plenty of options, but fewer then under 25'
>35-45'+ with planning, many options available. In popular areas, make reservations
For great access, the 4X4 Truck and camper provides some unique opportunities.
-Going into Canada. Follow the rules. You can take dogs and guns in, if you do it the right way. Taking liquor too, just be prepared to pay if asked. One of the reasons we crossed the border in Alberta, is if the do decide to charge you, it's a much lower fee. As mentioned a few times in this, and other threads, do get your paperwork in order. Many resources on what this means.
No matter what, answer all questions asked (and wait for them to ask) honestly. Also off the top of my head, after talking to many along the way on just this one trip, most that came over the border with all in order, were not asked to pay duties or even have their bear spray confiscated. (We are in that group.)
-As also mentioned in many threads, the key to protecting your rig, is to SLOW DOWN when needed. 45', truck toad with bike in back, are all heavy - so some sections you will just need to crawl your way thru. But, that's OK:)!
Will you have damage? Who knows:)! We did get our windshield 'peppered' in Fort Nelson by a a gent passing us at double the speed limit. He cut in very close to our front end, and according to the glass person we had repair our dings, it sounded like this guy knew he could cause some damage by doing so. You know what, it does not change a thing in our opinion on the trip being worth it. We could have had this happen in the lower 48 too - borders do not control jerks.
So again, I suggest go for it. My only suggestion would be to wait and do this trip next year, and allow three months or more if you can:)!
Opinions do vary, and only you can decide if you want to make this trip. Best of luck on your decision.
Best to all, travel safe, have fun,
Smitty