This is a general comment - not aimed at any of the previous posters. 
  
 I try to be legal in what I do but find it difficult to understand the complexities of driver and vehicle licensing in Ontario. In extremely general terms, if your combination of towing vehicle, trailer and loads total less than 4500 kg and are operated safely life is fairly simple. Once past the 4500 kg threshold, and in some cases sooner, life gets more complex if you want to be in full compliance.
  
 As with almost all regulations there are complexities. 
 To use an example from 
http://www.mto.gov.on.ca/english/tru...icle-faq.shtml question 16:
 
"If the trailer weighs more than 2,800 kg (6,171 lb.):
 - register the truck for at least the combined weight of the truck and trailer, weights A and B
If the trailer weighs 2,800 kg (6,171 lb.) or less:- register the truck for at least the weight of the truck (weight A), which includes trailer tongue weight
- weight transmitted directly to the ground by the trailer is not included in the RGW"
 In other words, if the trailer is light enough, its weight does not have to be included in the truck's registered gross weight.
  
 For anyone treading the thin line of legality, probably quite a few of us (me included) given the weight capabilities of modern pickups and the solid build of many MVs - please don't take my post or even the MTO website as the definitive answer on what you can or can't do legally. Please check the legislation and regulations listed in Q4 of the same website (not all regulations apply in every case but even that might not be the full list).
  
 
Highway Traffic Act: 
 and 
 Regulation 629 Accessible Vehicles
 Regulation 199/07 Commercial Motor Vehicle Inspections
 Regulation 424/97 Commercial Motor Vehicle Operators' Information
 Regulation 577 Covering of Loads
 Regulation 340/94 Drivers' Licences
 Regulation 587 Equipment
 Regulation 555/06 Hours of Service
 Regulation 11/04 International Registration Plan
 Regulation 611 Safety Inspections
 Regulation 612 School Buses
 Regulation 363/04 Security of Loads
 Regulation 381/98 Special Permits
 Regulation 618 Specifications and Standards for Trailer Couplings
 Regulation 628 Vehicle Permits
 Regulation 413/05 Vehicle Weights and Dimensions - For Safe Productive and Infrastructure-Friendly Vehicles
 
Transportation of Dangerous Goods Act
 Fuel Tax Act
 Public Vehicle Act