I reverse towed my S2 a lot when I was sprinting it, never gave it a thought, towed at 70 to 80 most of the time at night, mainly with a BMW 528, the car / trailer combo didn't like being towed by my mates 3.00 or 2.8 Ford Granada saloon.
the only problem we ever had was on the A34 (main trunk road from the north of England to the very south) when when a car overtook us then realised we were longer / going faster than he thought, he wanted to turn accross in front of us, I watched him & had already started braking, he then braked to drop in behind us but I was braking harder, finally he released his brakes & turned across in front of us, nearly had 2 cars smashed & the Europa come adfift from the trailer.