Check the fine print in your insurance contract. There will be something there indicating that the insurance is valid only if the vehicle is compliant with all laws governing its equipment and it use. Those laws, in connection with brakes on your tow, will be found in your Provincial or State Motor Vehicle Act. If you have a major loss, your insurer will want to know that your vehicle was fully compliant and may have an investigator ask the tough questions. If found to be non-compliant, your insurer will have a valid excuse to refuse payment.