Hi David,
The chart may be misleading as it is for 'resting voltage'. That means no charging and no use for 24 hours. That's fairly hard to do in an RV that is in use.
Just because it is a Tiffin doesn't mean the converter is a good unit--though you appear to have some encouraging results. (i.e. 14.4). If the batteries are the flooded type, then 14.8 may be better.
Shutting down the generator after bulk charging is what most folk do--but it is important to get to 100% state of charge at least once per week. Most folks find a campground and plug in for a 24 hour period.
What type of batteries does your lovely RV have?