No problem using the dogbone - the converter/charger load isn't high.
You would want to be careful using high draw items (microwave, a/c, electric water heater, electric heater...) through that setup.
As Ag&Au said - the quality of the converters in some of our RVs have been questioned... (I'm being nice..
With a proper disconnect (leaving no draw on the battery) - there should be no need to have it continuously plugged it while not in use.
Some of noted a continuing draw on the coach batteries even in 'store' mode - adding a true disconnect or leaving plugged in would be needed in those cases.
I don't have the luxury of electric where I store... but have never had an issue without plugging in a month or more... (Longer than that I typically try to run the genny for a short time - which also tops off the batteries.)
I'm considering at least a small solar setup to provide maintenance - but haven't really seen the need yet.