About a year ago I saw a few vehicles with Ontario plates towing trailers with boats behind them. I knew you could do it with a fifth wheel but upon checking with the OPP and the Ministry of Transportation was told it's illegal. Well had a camper leave the park today with a pop up and towing a trailer behind. Did some checking and found this on the Ministries website.
Towing More Than One Vehicle
Cars, passenger vans and SUVs are not permitted to tow more than one trailer
or one vehicle. Motor homes, trucks, pickup trucks and truck campers are
legally permitted to tow two trailers or a trailer and a motor vehicle
behind a trailer. However, a three vehicle combination that is swaying
excessively, is unstable or has reduced handling capabilities is subject to
action by the police as an unsafe combination of vehicles under the Highway
Traffic Act.
The maximum length of any combination of vehicles is 23 m (75' 6").
Either the law has changed or one hand doesn't know what the other is doing.