I think
brakes on a trailer are almost essential. I drive a Savana van that should have no problem towing my 4500, but I sure notice when the brakes are connected. The trailer helps stop the van, as opposed to having the trailer push you through an intersection.
Princess Auto sells brakes that can be installed, assuming that you have the square plates on the axles that the brakes would mount to.
3,500 lb Electric Brake Drum | Princess Auto
3,500 lb Electric Brake Assembly | Princess Auto
At $200 per side, you might want to consider a new
axle, with brakes supplied. This cost me about $1000 in Calgary, but there are places that can do it for less. The
axle is one of the big maintenance items on an old trailer. They do need to be replaced, eventually.