Our "solution" is just to move into the camper (in the back yard) if there's an extended power outage. Built in propane heat and refrigeration. Battery power will last a couple of days and it's possible to recharge from the tow vehicle, although a generator would be nice. AC power is needed to run the microwave or the air conditioner; but we could get by without those for a while.
Since the camper is designed to "plug in" to a single outlet, thre's no problem with isolating from the power grid and connecting a generator is trivially simple. A 3,500 watt (3.5 KW) generator would run the microwave or the air conditioner; but not both at the same time. A 5 KW would likely be sufficient for both at the same time.
The cost of owning a comfortable unit "just for emergencies" probably isn't realistic; but if someone has one - even just nearby - it could be a quicky solution for the people's comfort*.
* "Comfort" probably is a euphemism for anyone not accustomed to camping on wheels. After living in ours for a couple of months for our recent move I'm not sure I could get LiK back into it for any thing short of a major disaster, although the cats and I would be comfy enough.
Unfortunately, this doesn't solve the problem of protecting the house water systems from freezing or keeping refrigerator and freezers in the house running. There's a separate thread with some good links for shutting down to leave a house for short times, but it can be a fairly good piece of work to actually do a "winter shutdown" that will protect things without some auxiliary power.
The freezers and refrigerators could be unplugged from the house wiring system and plugged directly into the generator. The heating/water systems would require a safe way to disconnect the "hard-wired" connection to plug in, but separating out a single circuit (fans and thermostats?) might not be terribly expensive.
If a smaller generator is used, the systems/appliances could probably be run one-at-a-time to keep things safe, since they'd only need to run for a few hours each during a day; but this would require someone to unplug and plug extension cords, or a really heavy-duty switch panel attached to the generator. If device swapping is done efficiently, your generator only needs to be large enough for the "largest device" that needs to be cycled in and out.
If you decide to use the "extension cord" method, you should be careful about using cords appropriate for the loads. Although the hardware shops sell AWG16 cords 100 feet long, I don't consider those adquate for much more than a small weedwhacker. To run a refrigerator at 100 feet you need, as an absolute minimum, at least an AWG12 cord (15A 110 VAC) and to be really safe - especially in variable weather - I use AWG10 to plug in the camper (20A 110 VAC). AWG10 cords are about the diameter of a garden hose and run a little more than $1/foot (on sale?). You likely will want more than one. A 100 ft AWG10 "contractor" cord is about 30 pounds to lug about. Good connectors require some strength to connect and disconnect properly, and may be a problem for elders (like me).
A suitable "get-by" system is a compromise between convenience and the maintenance and tending required while it's being used. You'll need some serious study of what you actually need and quite probably some advice from knowledgeable persons who can take a fairly detailed look at the house wiring setup you have. The help you need should be fairly readily available, but it will take some time to dig it all out and make the plan.