Re: What's the deal with 2 trailers?
I don't think there's any law banning it in NJ, I pulled two trailers in tandem back from NY a few years ago. I had a cut off pickup in tow when I found a boat for free on the way home. I hitched the boat to the ball still on the step bumper of the pickup trailer and off I went. I hung a spare trailer tag and a set of clip on tail lights and all was well. I was approached by an officer at a rest stop and other than being amazed, all was fine. I think he just wanted to see how I had it all hitched up. Backing up is not an option, but my alternative was a two hour drive back to get that boat, that wasn't worth the trouble or gas.
Neither trailer was very heavy, I still wasn't towing more than about 1500 lbs.
It all towed pretty well, no sway or other adverse problems. I could feel the second trailer buck the first one a bit on big dips or bumps but there are few on the open highway. It was only once I got back home that I got off and had to negotiate a few railroad crossings and rough crossroads.
I dropped the second trailer first not long after getting off the turnpike. I went back and got it the next day. I asked a few local police about whether there were any laws and none could find any. The only thing that could really apply would be something along the lines of "Loaded to spill" or creating a traffic hazard" if they deemed the rig unsafe.
I am sure the ideal situation would be to have electric brakes on at least the second trailer, that way you could straighten the whole rig out if it got out of shape.
On the back roads here, I've towed as many as three locally, but never in traffic or around town and only empty trailers. I doubled up a boat trailer off the back of my flat bed car hauler the other day too, but the second trailer was hitched to the bumper of the truck on the trailer and the truck was secured with axle straps and chains. It did just fine, I passed several police on the way back with it, none paid it any mind. It towed fine behind a half ton truck, but again, no serious weight or speed. I'd say top speed with that load was only about 40 mph or so and it was only about a 10 mile ride.