an '09 Diesel Pusher with only 19k miles in over 12 years is probably not good - so little miles means that it's probably been sitting WAY more than it's ever been used... send a link to it's ad and we can all see 'more' details about it.
- 'days' off-grid with only the water tank and holding tanks is totally up to you, there's no way for anyone to be able to guess that - the size of the tanks, how often you use them, etc.
- campgrounds and rv parks range anywhere from $20 to $120 per night, depending on where you are going, whether it's a 'resort' or just a basic park, etc.
- being 'parked' for long-term means you want to hook up to the 3 basic utilities - electricity, water, and septic/sewer. Septic tanks/sewers are the most problematic, though many homes have external 'clean out' plumbing outlets that are the same as with any campground or rv park. Electricity is easy - whether you simply run an extension cord from your home for limited power, or you want to spend money to run a full 50amp RV outlet from your Main Panel, for full power. Water is fairly easy - just a long water hose from the house.
- 'good condition' is subjective, only YOU can determine what that means for you. I would be concerned about the few miles over 12 years and whether the oil has ever been changed even once in this engine, though it could still be a good engine/trans combo - inspecting it closely will be warranted - take a diesel mechanic friend with you. Crank it up and let it run for a while - take it for a test drive, of course. Diesel oil changes usually are 15,000 miles or so, but more costly since there is a lot more oil, though Speedco and large truck shops can do them easily.
- the Generator is of concern, also, as I imagine it also has not been used very often, but the same applies to it since it is, after all, a small engine, too. Prime it, crank it, let it run for quite a while, and run the air conditioners both for a while to give it something to power to show that it is still capable of handling them easily.
- generally things don't 'break', but maintenance and any issues will determine 'where' you go - engine/trans/generator/chassis related issues will be handled by truck shops/freightliner/cummins, etc. 'RV' interior issues can mostly be handled by mobile rv repair or rv dealerships.
- Depreciation is also subjective. You're already buying a 'depreciated' vehicle, so it will continue, but at a slower pace. Older RVs certainly don't hold their value any more than any other type of vehicle, unless they're a 'vintage' Airstream, maybe. Larger motorhomes are harder to 'sell' simply because they are a lot more money compared to other rvs.
Without photos, a copy of the advertisement, and more details about the pricing and any current issues that the owner is stating, it's hard for anyone to really comment on this specific motorhome, though it sounds like a good one.
...2014 Ameri lite 259BH...
towed by our '14 Thor Palazzo 33.3 diesel pusher...