Do you read the cartoon Crankshaft? He's a bus driver that knocks down Keesterman's mailbox regularly. ;)
A 5er may make the turn better, which is definitely a consideration in your driveway/mailbox situation. You will definitely want a spotter, or frequent stops to look, for the first time or two, either way.
With your epoxy/pea gravel driveway, I would have a couple good-sized sheets of plywood handy for the first go at it. If you get too close, you can put the plywood under your drag legs, and keep your driveway from getting gouged. I don't think you will drag, based on the pics, but I sure would be ready for it, just in case.
Enjoy your new TT, whichever way you go. Look like any of them will be quite comfortable!