The generators on there are actually higher output and tougher than alternators. It is true they don't charge at really low RPM but its more like 1000 RPM or so. I idle at around 1300RPM (Geared Engines :-) and mine are outputting as soon as I start up. I have no plans to upgrade mine and honestly you don't have the problems with them. They are built like tanks.
Keep in mind, those things used to run lots of huge electrical drains on your plane that have now been replaced with tiny micro boards. So I'd bet what you have would be capable of running an air unit in its sleep. Maybe not, but I'd look into it first.
Glenn