The Elec. here in SE Asia can be a little unreliable, so it's common even for a rental to include a backup gen.
How the cabling is arranged relies entirely on the skill and imagination of the person doing the job.
"Safe" operation relies entirely on the user understanding the shortfalls - eg. the feed-in socket in the meterbox is always hot (no changover switch), failing to remember to turn off the meterbox isolater will result in trying to power the neighborhood with the gen (and of course, the gen will smoke when the supply is restored).
What could possible go wrong?