I typically field my Mad Dok with a unit of Burna Boyz. I figure they’re an elite choice, so they can’t hold onto objectives, so i don’t really look at the whole “crazy- have to attack everything” as a negative. Plus, with the Dok, they benefit from being Fearless and Feel No Pain. My Burna boys just became the statistical equivalent of marines with power weapons. Good stuff. 
Of course, Burnas don’t get their own trukks. So they have to “steal” them from a unit of regular boys, or get a dedicated heavy support lotted wagon. I went with the looted wagon with a Skorcha, Reinforced Ram, and Open Topped. It’s fast enough (not a trukk, but that’s ok), gives me a transport that anyone can use later in the game, and it has a heavy flamer. Again…. good stuff. You really can’t have enough flame templates in 5th edition 40k.
Conversion wise, it is an Imperial Guard Hellhound, with front plates from a Stompa, a Skorcha from a Killer Kan, some old Bad Moons icons, plastic card, and resin track links from Iron Dog Studios.
