In truth you cannot really do this because range is a function of drag, not really weight.
So if you are towing a 2000lb empty box mobile home it's gonna be worse than towing an 8000lb flat bed of decorative boulders.
AgingWheels on youtube did a video testing exactly this.
Yep. It takes a massive battery (and massive "normal" range) to pull off towing any distance. Unless I'm wrong, only the Chevy Silverado EV has the range (480ish) to make a reasonable tow vehicle, but only with the big battery, which pushes the price north of $90k.