What model year is your 170? Some would have a bi-directional battery separator (Sure Power brand iirc) under the hood that should allow charging both the chassis and house battery when the RV is plugged in.
The 2004 190 that I had did not
have the Sure Power separator. It had a Herr isolator that was not bi-directional. It did have an OK 3-stage charger so I used to plug the RV in at home to maintain the house batteries and, because the coach had AC power, I could plug in a Battery Minder inside the RV and use a 12V accessory plug to maintain the chassis battery by plugging it into an outlet in the dash.
There's a photo in this topic: http://www.classbforum.com/forums/f5/connector-630.html