I was at VGF about 3 weeks ago.
There is a path all the way from GF, past the Wedding Pavilion, thru Poly, and on to TTC. It's an easy walk, just stay close to the lake, and don't go thru the Wedding Pavilion parking area. The path is between the pavilion, and the building where wedding arrangements are made.
There was still plenty of beach at the Poly to watch the fireworks without being bothered by the construction. (Don't know if/when that might change.)
Another possibility is to watch the fireworks from the GF boat dock. It's closer to the fireworks, but the fireworks are more 'centered' at the Poly.