As to which first would agree patient dependant. As to doing 12 lead then IV while rolling, I got to say that is some of the left over golden hour idea attitude, a subject recently discussed. Being so far out we spend time on scene doing as much for the patient w/o fighting the bouncing ambulance. It's safer for the medic and the patient as both can be properly secured. Then enroute we just monitor and administer the next dose of meds ivp if needed. Can I do it bouncing down the road? Yes, but why. Why risk a missed IV or getting stuck with the dirty needle when your driver hits a rough spot. Why risk being thrown across your patient. I'm not so macho as to think someone is less of a medic because they stop and use common sense. I say do what you can on scene for safety sakes, my safety comes before anyones. Are there times I still end up doing things going down the bouncy road, yes but I limit how often.