Salvor.... I would recommend you look into LIDAR info... if any already existing on that area... which would likely reveal in good detail the site locations you seek.
One... there MAY be some that already exist in county and or state records... many of which are public and accessible online... some can also be obtained through requests as well.
IF need be... and afforded... it can be also be easily bought... and possibly even seen for free through any one of the many LIDAR Co's that are cropping up everywhere.
LIDAR is your best and fastest way to find those locations without boots on the ground IMO.