Red diesel
Don't wory about switching pump and hose unit from tank to tank. The red will not stain the hose or pump. As soon as the red is out od the system there is no residual effects. I have red diesel tanks for the tractor and duce that is used off road. I also have a pick up that I fuel from a seperate tank , (on road diesel used), and I switch the pump assembly as needed. The small amount of red in the system ( less than 1/2 cup) is quickly diluted into the on road diesel.
If you have filters on the pump system, those will need to be drained to remove red before going to on road.
In 38 years, I have never been checked by police for diesel fuel violation. Other violations- yes. Diesel- No.
RG