I think some good sense needs to be employed here.
The website Guzzilazz points to I have no doubt is an honest piece of work, and it probably does describe the way a battery will react to the discharge and recharge cycles. Let me be clear, I am sure that treating a battery in the way they suggest will probably maximise its effective working life.
But unlike boats,caravans and their occupants even those being used off grid, are rarely placed in jeopardy if the 12V power fails, so redundancy and vast over capacity is not warranted nor wanted becasue of the effects of the weight of carrying extra batteries.
I am not advocating total disregard for the care and management of batteries in caravans, and there is nothing wrong with applying all the care Guzzilazz's web page is suggesting, but from a practical perspective caravan owners do expect their batteries to wear out over time. But It is very difficult to establish what the life expectancy of a caravan battery should be.
We have heard of batteries that have lasted many years beyond what might be reasonably expected, but we have also heard of some that have failed well before teh warranty period is up, but that is usually due to a faulty charger.
Caravanners are expected to use "leisure batteries" which are a derivative of Traction batteries. These are designed for long relatively slow discharges as would be experienced by an electric Milk Float (If you are old enough to remember them). These were charged over night, and expected to provide continual discharge to move the float around teh delivery route. They would return to the depot significantly charge depleted.
I would expect to be able to use virtually all the charge capacity of a caravan battery as I describe in an earlier answer. It might shorten the lie of a battery, but if it enables of grid caravanning in the manner you desire, Then go for it.