Haven't camped in a caravan park for donkeys, so don't know what the standard size site is (or even if there is such a thing
), but any other campground worth it's salt should be large enough to be able to cope with the larger camp setup's.
With a 7x9 tarp however I'd imaging you'd almost be able to provide shelter for the whole camp ground
We have a 2 or 3 different size tarps that we use depending on where we go and on how long. They don't cost all that much and have a million and one uses around the home, so worth probably having a selection on hand.
Have a mate, also in Tumbi, who incidently has a mate in Tumbi named John, two kids, used to (don't know if still does), drive an ol holden. Ain't the same john ?