what, slow down? why?

So, Cap'n John has been loving the 80 mph speed limit on I 90 through South Dakota.  Construction sites the speed limit is 65 mph.  Remember our RV is 40 feet long and towing a full size SUV with 2 large bikes hanging over the back.  Over these couple of years, we have been required to travel through some pretty ridiculous road construction.  Sioux Falls, SD threw us in this with no warning: 

He literally did not bat an eye and was rockin' out like a boss.  How does he do this? 
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