You are not alone in your quest to conserve 12v battery power because shore power isn't around enough. The general consensus is to plug the front TV, DVD player, camera chargers, cell phone chargers etc. into a power strip with an on/off switch. This way you can easily control your 110v usage. If you study my picture closely, you can see how NOT to do it. I corrected it after the picture was taken, plugging the TV into the power strip..
Many things use power continuously like the antenna booster, fridge, and your invertor. We turn off the invertor at night using the small switch on the invertor itself. I wish there was an invertor kill switch in the battery control panel. The fridge along with all 12v lighting gets power direct from the battery, even with the invertor turned off. Turning off the invertor assures all 110v is dead.
I modified the invertor access door to work like a regular cabinet door with a latch. Phoenix USA must have screwed it shut for child safety, but we have no little ones. If we later have grand children, I will install a child safety latch.
To "Fast Charge" the batteries, I bought This Charger at Wal-Mart for $93.
Specs Here: http://www.blackanddecker.com/ProductGuide/Product-Details.aspx?ProductID=17925
This Black & Decker charger has a 40 amp setting which the manufacturer states is recommended for RV applications. The RV's invertor amperage is much less. Both the invertor and B&D charger are "Smart" chargers so there shouldn't be an over-loading condition. I am told, using both the invertor and this charger together will be both safe and effective. I will find out first hand on our next big trip. Many RV owners said that supplimental charging this way should help a lot during short 1 to 2 hour generator runs.
The name of the game is to never see red on the battery monitor. To me getting a solid yellow means danger..."Turn On The Generator And Get Out The 40 amp charger". If the battery indicator on the RV goes yellow/red, you are too late to build up adequate reserves in short time. If it goes solid red, you are in real big trouble. We went solid red and our fridge was going dead on us over-night, even after being plugged in at a private campground the night prior.
Once we got back home, it took nearly 3 weeks on a 10 amp charger to get them fully charged.. Never again do I want to see red on that indicator.