If you plan on boondocking a lot get yourself at least two 6 volt deep cycle batteries. You are right about it taking a long time to get a battery fully recharged using a generator or any other method as far as that goes. You are also right about the crappy WFCO converter. You could replace it with a good Progressive Dynamics converter or a high amp battery charger. The best way to go is with the new converter. Regardless, if you let your battery go dead as you did it takes a long time to get it recharged.
Or get solar.