I haven't observed ANY DP owner running their engine for an hour, but I hope this helps answer your question. A DP engine does need to run long enough for the air suspension to come up to ride height, and to allow the brakes to come off. Without sufficient air pressure, the brakes won't come off, and the DP is going nowhere.
Here are a few things I do to try to mitigate the annoyance for neighbors:
1. If we're only staying overnight and we're on a reasonably level site, I don't 'dump' the air. That usually means I can't/don't extend the jacks (because the coach is "too high"), but a little rocking during an overnight stop is not a big deal. Since the air wasn't dumped the night before, the suspension and braking systems usually have sufficient air pressure in the morning for me to start the engine and drive off.
2. If I'd dumped the air for whatever reason, I'll run the engine long enough to bring the air pressures up high enough for the 'low air presssure' alarm to shut off, then drive off slowly to let the air pressures come all the way up before we hit the highway. If necessary, I'll stop and fast idle outside the campground.
3. A version of #2 - I bring the air pressures up and shut the engine off until we're ready to leave.
4. If possible, I'll delay our departure beyond "early" in the morning, unless I used #1 above.
I've consciously employed one or other of the above every time we've left a site.