RE: Onboard Charger
I've been using one of these for over two years now:
http://www.progressivedyn.com/power_converters.html
I first had the 9130 (got fried by bad wiring at a campground hookup) and
now have the 9140 and the Charge Wizard.  Works great.  Hard wired to the
aux battery it fires up and charges the battery whenever I'm plug into shore
power or if in the boonies and I fire up the Honda and plug it in.  There
are others of like quality on the market, most more expensive IIRC.