Gasoline: 3-6/month shelf life
Diesel: 12/month shelf life
Propane: Indefinite
To get that out of the way, the problem is a gamble however conceived.
What capacity (several 100-lb cylinders or larger) can be addressed somewhat. Design guidelines and rules exist.
The function of an RV is to be (and remain) mobile.
“More” propane and a TV with “more” diesel onboard than was factory-offered to be the storage tank addition “might” extend one’s abilities where high cost isn’t a barrier, but it’s still going to come to the most favorable climate over preparedness in any event
Ability to run from NG isn’t something I’ve come across to power an RV as propane substitute. Using it to generate electricity to in turn be able to substitute wholly or in part is going to take a design/size/weight starts to get prohibitive.
IIRC, the engine hour count I’ve seen on some 1980s-era Bluebird Wanderlodge diesel gensets was 12,000 or more. (500-days at 24; or 1k days at 12).
50A service = 12kW (equivalent max). An ONAN that size is $14,000-MSRP (rough; maybe $11k at dealer). Now factor oil/filter changes every 50/hours. And that the warranty is void if used to power a house in any fashion. 7-800/lbs.
Fuel consumption is going to go from .5/gl-hr at half-load to .8/gl-hr at full load.
All the numbers can be manipulated. But size/weight/consumption are all still a barrier beyond incorrect Genset spec for non-RV use.
Use the RV versus the house, short-term. Acquire additional propane bottles with proper transport addressed (least likely), to power the RV. What solar could be added is high-expense with low reliability (long-term) before that systems shortcomings in less than ideal operating conditions.
It’s genuinely the house needs to be addressed, not the RV (past maximizing its systems ability/capacity to ensure longest occupancy for a given power source). Natural Gas appears the best backup if that’s feasible. (Takes electricity also, even if remote).
Use the RV as family Conestoga to get somewhere better. Warm, dry quarters with all other amenities in the preservation of dignity it’s highest value. Assume injury or illness, that value goes higher yet. The inputs to maintain those keep one’s independence greatest till the day they don’t is in a plan which combines greatest distances on the one hand, and maximum nights-aboard times X-persons on the other.
Q: Better to have asked — and prepared; tested — what would it take to ensure complete freedom from any re-supply (food, water, propane & TV fuel) for a family with X-members over Y-nights aboard. Is it 10-nights, or is it 30? What are the differences? (In disaster planning for hurricane evacuation TV MPG — actually, any vehicle — won’t rise above 3-5/MPG . . and 150/miles from the coast is the minimum to access operating fuel stops).
With a bare reserve remaining, how far could we go, and for how long?
Promises to homeowners that, “be patient, we’re working hard to get the lights back on”, can become lies when two weeks turns into two months What MAY matter most — then — is leaving. (IMO, keep that option foremost).
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