Umn, I wasnt' advocating driving under the speed limit. There are places where the speed limit is 75 for all vehicles, but you'll notice that most of those places are pretty wide open as to the traffic and conditions. But 70 in someplace like the I-5 corridor in Washington (for cars 70MPH for trucks 60MPH) is stupid. Traffic is often very dense and you have one to two car lengths between you and the car behind you and in front, the next lanes are the same and there are between 10 and 15 cars around you... So, going the speed limit for cars in your truck/trailer (perhaps like mine your CGVW is 22K) and you've got to react in the same time as a sedan... because that's all the space you have. You may leave a safe following distance, but it will get filled in by those 'cant stand to follow an RV' drivers who pass you. So you're left with nearly no space, much higher stress levels and no time to react in a emergency.
I've towed many miles too; never had an incident, never had a blow out (after all normal travel trailer tires aren't rated for high speeds - generally less than 75 MPH) and I haven't caused any incidents by going the speed limit.
People with your attitude become statistics. People with my attitude live longer, stress free lives.