@DigitalDad just mentioned the things I was thinking of. It is hard to reregister a car if the home state requires inspection (not impossible, just hard). I lived in Florida and there were a ton of OOS plates because of military members, but in other places it is hard to get a parking permit, a toll sticker, a beach permit.
I think for 2.5 years I’d become a resident. If she does qualify for medicaid, she’d need to be a resident. Other services too. Just so much easier to get a library card, vote, get a resident rate at the local park/rec center/gym. Here you even get cheaper rates for tee times at the city owned golf courses if your license has a city address on it.
Her insurance (both car and health) rates could be much cheaper in WV than if you live in a west coast city.