I work for a fleet owner who has 8 trucks. He has migrated from D's to C's and all are C's at this time. And, more to the point, they are all WG and TVAL with all of encouraged to get Radmat/Explosive and DoD qualifications.
Point being, when freight is slow, being able to handle the niche markets which vary less than the overall market you can still pick and choose.
Last two months we have averaged $1.90/mile and 24.5K/month. The only real impact on the slower freight for us has been our DVA, which is running at 30% right now, but the load offers keep coming regardless