If you are thinking of living in an RV say on a spot along side a house, like your relative, yes, that's possible. I ran a 30 amp outlet behind our garage for visitors.
You could run a hose from the house and have water. Your camper would have separate tanks for grey and black waste water. They'd require frequent emptying.
Insulation is poor in campers. They are cramped at first. Later, with children, suffocating IMHO.
You'd use a lot of propane, not cheap when filling small tanks.
My wife and I have lived for four to five months in our 36 footer with all the amenities and no need to pinch pennies. And good weather. We're always glad to return home in spring.
I think it's not a good plan for your family. Your expenses would almost certainly be higher than you think. Where are you staying now? If you've sold your home or are in an expensive apartment, a
cheaper apartment would be a better choice.
Good luck, whatever you decide.
