I'm running 19's and I have found that sweet spot after great expense.
The secret recipe:
30m Drop
19x8.5 ET45 all round.
Running 104 rated 255/45/19
Giving this as a look if it suits you.
View attachment 16846
The van never bottoms out, and it never rubs or catches.
I have gone across a field with no issues.
It's planted at speeds, yet very comfortable.
Laymen's terms it's 2 fingers between the tyre and arch at the front, and 3 at the back, giving tolerance for any extra weight in the rear if needed.
(oh and I don't have huge sausage fingers)