There's nothing wrong with runnin' slow... Pretty peaceful once the traffic gets by you... Plus, you won't have to wash your windshield as much. Bugs don't splatter on windshields at 62 mph... Relax... Ease the seat back and enjoy the ride... Besides, it's their damn truck and their damn freight. I wouldn't worry about it...
Oh yeah... About the cruise control (or lack thereof). You all have cruise control you just don't realize it... There are cruise controls laying around outside everywhere you look... A BIG ROCK!... When we drove those hi-speed hay rakes (Internationals = too fast for the farm, too slow for the road) over here at Yellow, you absolutely could not drive continuous in those things with no cruise control because the fuel pedal was right under the damn steering column and you had to sit side saddle in them to work it. If I got one that the cruise was broke on, I'd stop somewhere (safely, way off the road) get on the ground, look around and find a big rock. I'd heave that rock up in the cab, throw it in the floor, smack 'ol yeller on the a$$, get her to a full gallop and "kick on the cruise" (kick that big rock over the fuel pedal). Just be sure to position it in such a manner that you are able to "kick it off" quickly & don't use it in town!...
I pulled up in Memphis one morning ridin' one of those things. The cruise didn't work so I had stopped on the way & found a cruise for it. After I arrived, I had gotten my saddle off of that war horse and was walking to the dispatch office when a yard man, who was getting in that tractor to break it down, yelled "hey driver! you forgot your rock"!... I yelled back, "that's the cruise control, it stays with the truck"... That damn rock was probably still laying in the floor of that truck when they got rid of it...