GordonThree, a Tiffin RED is not considered 'high-end'. It's an entry level diesel pusher. They are nice, my brother just traded his and moved two steps up to a Tiffin Allegro Bus (second from the top of the Tiffin line).
TeamNash, you will have to run the generator twice a day as mentioned previously. If you want to use the air conditioning, you will have to run the generator while the air is on.
Keep in mind, that the Tiffin RED has a 5,000 lb. towing capacity if that is of concern.
Wet cell batteries have to be checked at least once a month and will need to be topped off with distilled water as needed. I would switch to AGM's when the time came to replace the batteries. They are more expensive but you won't have to worry about 'watering the batteries'. Also, wet cell batteries sulfate too and will need cleaning monthly (from my experience).
To get more life 'off-grid' boondocking, you would need to add solar panels and possibly more batteries (if there is room). The Tiffin RED has a 100 gallon fuel tank so it will last a while running the generator.
Good luck,
MM.