I just traded up to a 2010 3500 dually and need to setup my 7-way plug in the bed(slide in camper). I know on past Dodge Rams the battery lead on the 7-way is always hot.
Does anyone know if this is still the case on the 2010's?

 

Yes it is.

 

I'd suggest getting a kit that uses the factory plug where the wiring harness connects to the stock 7 way bumper plug.

It saves a bunch of time, and you don't have to alter/splice into the factory wiring.

The plug is always hot, so you may want to add an isolator.

 

How would you add an isolator?

 

You can get the 3rd gen in bed plug relocation kit from e-trailer for around $60. I don't know if it's available for the 2010 year model yet.

 

An isolator can be installed under the hood, so the truck charges the RV battery after the truck's starting batteries have been recharged.

You could also use a relay to cut power to the trailer charge position when the key is off.