Potter's Creek Park. I drove through there today and the best campsites in relation to the water do not have any trees, however, there is a covered picnic table on each, so there is shade.
There is a map here
http://www.recreation.gov/nrrs/Pott...dMap.do?camparea=MAIN&agency=NRRS&parkId=5020
I would recommend sites 115-124 (specifically 121-124) due to them being on the end of the point. These are tent sites only and we would need 4-5 of them I would guess, since each site can only have 2 vehicles and up to 10 people. For those bringing RVs...sites 105-114 are right there as well (specifically 107-109).
The sites that have trees are further from the water (66-81).
The other good spot would be sites 62-66. These are family sites that can have more vehicles and up to 20 people.
Works for me!