2019 Cross country RV trip planning

Thank you guys. All the responds are quality and helpful. Just start planning, Wyoming/Montana have lots of mountains? Haven't do reseach about that yet, never been there :? If that's the case, we may give up Yellowstone. What's the best flat route from NB to BC? Thanks in advance. You guys are awesome! Since the truck has bought, we have no plan and no money to get a bigger one. We have to find a way to make it happen since we need to settle down in BC at the end of the trip. Change transmission oil, get a transmission cooler, slow down, take less stuff with us...what else can we do?