As long as you drive through the two block areas before the sign or the sign block itself it is allowed (see the yellow boxes in the first post)
If I see it correctly the car jumps through the edge of the house? Then it counts
Here are a few examples:
The car has to go through the yellow volume in any way at least once!
The same counts for all houses and signs:
This is a valid area for Stadium:
This area seems a lot bigger, because you cannot actually build something in the box area with the cursor