As long as it is not attached to an existing structure, I wouldn't be surprised if they do not require a permit.
Don't assume, of course.
If you are building from scratch, you'll have no problem making it strong enough.
Consider steel posts set in concrete with wood beams ( 4x8 or 4x10 ). They make lightweight engineered joists or you could just use 2x8 or 2x10 on 16" centers.
You could park cars on that.
Plywood deck with a waterproof membrane.
You could get wild and do a perimeter wall for privacy, floor drains, planting tables, BBQ area.
Sounds like a really fun project.
A 'build' thread is required
KT