Leave the fridge on gas. They draw 35 or more amps DC thru an inverter. That's a real battery killer.
The low budget setup would be a 1000 watt pure sine wave inverter. Hook it near the batteries with 2 gauge wires and a 150 amp fuse. Run a cord to what you want to power or install an outlet, wired to the inverter. It will make coffee ( my Mr. Coffee draws 700 watts ) or run TV and Dish.
I use a Xantre X PS1000. I Leave it on when using the MH, since it only draws 1/2 an amp.
From there, things get more complicated and more expensive.
I run my inverter thru a separate auto transfer switch to a few outlets, fed by 1 breaker in my panel. That way the charger, fridge, microwave and AC can't run off it.