Oh well, more posts for more peace of mind. Tied to garage in two places, to house in three. Off to do some calculations and dimensions.
I plan to make it a bit more decorative than this, but its too nice a day to be drawing latticework in Sketchup :-)
Solved the post vs car issue too. Two honking big ceramic pots, staked into the earth, overlapping the driveway by enough to shield the posts, filled w/ stone and earth and pretty plants. Kind of like a breakable bollard.