I don't think the artificial turf on top of the grass is a good idea.
Mold, things living under it, etc..
I removed a portion of the grass in my yard and use it to park the Southwind and cars.
I'm surprised that municipalities require a 'hard' surface. Most places limit the area you can cover with concrete, asphalt and structures.
They want the rain water to soak into the ground. Gravel makes sense.
But, we're talking about government so, we can't use the words common sense.
If you can install a gravel pad, that's way to go. It's quick, cheap and can be easily removed.