You only need 20 amps per battery for fast charging.
With 2 batteries 35a to 60a is plenty.
Give that WFCO a test before you rip it out. Run the batteries down slow with one light to 12.0-12.2 volts and fire up the generator. If voltage at the fuse panel steadily rises to 14.4 volts you are good to go. If it pops up to 13.6 volts and holds for an hour.... you may as well put it on ebay.
If your portable charger is 25+ amps it should get you through the trip OK running the generator 2 or 4 hours per day.
If you will be parked in the sun... consider 200 watts to 300 watts of solar. Portable is fine for now.