Hi
If you go for a new charger / converter, get a "4 stage" version. They were not available when your AS came out. These days they are very much the right way to go. They are not terribly expensive. You will pay for one with the longer life on the first set of batteries.
You can get "all in one" boxes that have an inverter in with the converter. They can be nice. They also may or may not be easy to wire into your setup. For the full feature set, hook up a transfer switch and get one with a solar converter input. No, I'm not volunteering to *pay* for all those crazy ideas
As always, check all the cables any time you do this sort of thing. Putting in $400 worth of electronics and missing a $5 chunk of wire is a bit embarrassing ... don't ask how I know ...
Bob