With the diesel pulling up through the gorge won't be any problem. What has been my issue is the narrow left lane and lack of straight road. I find it hard to pass trucks, so I don't. And I have found myself not towing behind some flatlander who would not pass or move over, so both lanes went 35. Fancy Gap (I-77) has a steeper grade east bound. If you really want to avoid the mountains go south to I-85 and back north, but that adds about 40 miles.
2018 Silverado 3500 DRW
2011 Montana Mountaineer 285RLD