And it's not the miles going uphill, but the elevation change. You calculate ten miles drain for every thousand foot gain (hey, it rhymes!). I gain a thousand feet in two miles going up to my house every day. Your quoted wind speed of "mild" means?? 10 mph of wind is the same as 10 more mph drag. And the range already drops 25% when driving 75 over 65. So, yeah, I believe your range is down to 150.
I would recommend watching Trips and slowing down. Unless you're not worried and are going less than 150 miles.