New poster here. I reserved my Lightning back in May. We have a 9,000lb GW toy hauler with an 800lb tongue weight. Hoping that the Lightning will be able to tow her ok.
Here's the first realistic data, not with a Lightning but a Rivian R1T:
The owners/drivers of Gideon the Rivian were pulling a trailer with a Mustang Coupe (trailer weight about 6,500 pounds) across country. In the first leg, TFL Truck identified about 7 stops in 700 miles from Gideon's Instagram account. The owners confirmed this and indicated they kept charge levels in the 16-80% range.
~100 miles between charges while towing
equates to ~ 165 miles total range while towing (100 / 0.6)
equates to ~ 45-50% range reduction from EPA range due to towing (314 mile EPA range)
Note that this is the reduction from overall EPA range. I haven't seen the EPA highway listing or an independent highway test. The YouTube discussion also didn't include what speed Gideon was traveling.
All in all this suggests we may see a 40-50% reduction from the Lightning's overall EPA range rating as well.