Amperage (amps) is a measure of instantaneous current, i.e. the current that is flowing at a particular time. Amp-hours is a measure of current over time. A current of 6.7 amps x 5 hours per day = 33 amp-HOURS per day.
Batteries may be rated in both amps (at different temperatures for cranking purposes) and amp-hours (for deep-cycle purposes).
It is also incorrect to make the blanket statement that AGM batteries do not need to be in vented enclosures. In an overcharge situation such as a shorted cell they most certainly do pop their overpressure vents and vent hydrogen. Although many do not use a vented battery box and get away with it, a few don't. I don't think any of the electrical equipment in an Airstream is certified for use in explosive environments. In particular, this includes the converters often colocated with the batteries.