Yes, drive for the road conditions. I often come up behind trucks towing a trailer or fifth wheel, and often see the back end of the trailer hitting the asphalt at frost heaves. The truck occupants seem oblivious.
Our fifth wheel's bumper is high because we "flipped" the axles so the trailer rides level on our 4x4. Even so, we're often moving along at 30 mph, sometimes 10-20 mph on the bad sections. Rarely do we drive the speed limit (55 mph).
Each spring the highway conditions change. This year the Alaska Highway northwest of Whitehorse has gotten BAD. It tosses my Honda Fit around pretty good, and is really hard on our F-250 with its harder suspension.