@2112, MitchF150 & valhalla360 - Thank you! I try to cruise a couple MPH slower than the speed limit so I can stay out of the left lane as much as possible which keeps us near what most semis are doing.
I really appreciate ALL of the advice! You all have calmed my nerves about it and we'll stick with what we've got for now.
Next time we're out we'll hit the scales first and I'll experiment with getting a running start when we approach those hills. Sounds like it's mostly experience and since this was our first long road trip with it, we were out of our comfort zone and worried we were going to break something :)