Same exact setup we had, right down to the gray Prius, but ours was an older '08 model with a 1.25" receiver. I wouldn't be too concerned with a couple thousand pounds behind most any small car in good repair, and the Bolt has a couple of pluses and a few minuses a as tow car.
- Short rear overhang
- Regen Braking
- Weight distribution
As long as you're pulling less kW continuously than the car alone running up the side of the Rockies at 85mph, your not putting any more stress on the vehicle drivetrain-wise than someone with a fat family who lives in the western mountain regions and drives briskly. I think it should take about 40kW extra
to move a max GVWR Bolt up a 9% grade at 85mph vs level, as a quick example. Having a low gear would be nice if you were starting off on grade.
The springs likewise will see no greater impact than a lone car with four fatties in it, unless you load over the 2,258 lb rear GAWR with the tongue weight added in. The short wheelbase give the front end less leverage to keep the front tires planted, but conversely the short overhang gives the tongue weight less leverage to lift/unload the front end. Short wheelbases also tend to get a bit more bucky bronco over the highway seams, and they put more lateral load on the rear tires in cornering vs. longer cars. The more even weight distribution the Bolt has is a minor annoyance for towing, as a front heavy car would put more of the mass over the front axle, helping to counteract tongue weight effects.
Other than that, if you exceed the GVWR with the total weight of the rig, you need to slow down to maintain brake fade performance, or install trailer brakes. There is no special engineering that goes into making small general purpose passenger vehicles tow rated, just a series of calculations that are done to come up with ratings based on some arbitrary formula - based on what the formula writer thought the average driver would drive like in that sales market. In the US we now use SAE J2807, which is fairy new and has the average American driver idiocy factored in. Obviously if you are going 5 mph, you can tow several tens of thousands
of pounds with a Bolt (or a bicycle with the right gearing for that matter) all day long every day without issue, as long as you have a way to bring it to a stop.