That is what my recommendation would of been as well. I would also look into installing a Xantrex linklite monitor gauge so you can monitor your battery voltage.
Here is actually a new 50A charger Xantrex makes that can simultaneously charge different types of batteries. It also has a battery temp probe and can be hooked to a Link lite and show you AH discharged, rates, voltages, etc...
With that new XS series it looks like you would only need 1 charger for your entire battery system.