What do you mean "overflow parking"? Like, where you would've parked your car for camping someone else will use? Perhaps so they can use more than one vehicle?
I don't understand. It's what space you're talking about that doesn't make a whole lot of sense to me.
And how important is the family? Personally, I'd tell em' to shove it regardless of what they say. No matter what space you're talking about, you're entitled to it just as much as they are. Just because you happen to be more space efficient than they are shouldn't mean a thing.
-Gene-