Could be time for an upgrade to a better more up to date converter that has a nice 3 or 4 stage charger built in. A new converter will automatically supply current to 12 volt DC and 120 AC based on if you are plugged into a power source or not. i.e. shore power or generator. No need to flip a switch to change between the two.
If you don't want to upgrade you converter you can easily add a solar system to your camper battery or batteries. It is a separate system from your converter wether you use your current one or upgrade to a new one.
The solar system is pretty easy to hook up. Solar panels from the roof are connected to a combiner box (used to add more solar panels in the future), then the combiner box is connected to a solar charge controller (preferably a mppt controller), from the solar charge controller you connect to your camper battery or batteries.
Hope this helps.