How to tow an early A?

Twice I have tried to tow an early A with a tow-bar, and twice it didn't work. Has anyone had success doing this?

I first tried on my 65 Dart, with brackets bolted solidly to the bottom of the frame rails. I needed to tow it to the DMV, so tried once around the block. After each turn, the wheels decided to not follow, and went full over, making the tires skid. I later found a crushed-in rear inner fender and suspected the rear tire had been rubbing on turns, causing the problem.

Today, I tried to tow a 64 Valiant. It will actually drive, but my son was too occupied with friends to help, so I brought the tow bar in case I bought the car (did). I removed the front bumper and attached the tow bar to the bumper brackets. Same thing, but worse. The front tires didn't want to follow, except this time rather than skidding the tires, the bumper brackets bent sideways and one even broke off (brittle cast-looking metal). This was just testing it a few feet in a gravel driveway. I now must drive the 90 miles back tomorrow for the car, and beg a son to help (no mass transit).

I know that "caster" is the "shopping cart effect", i.e. that the pivot axis for the front tires should ideally hit the road in front of the contact patch. We don't have enough caster in our early A's since the steering was designed for bias tires which flex backward when travelling. Indeed, we often have negative caster. Positive caster isn't what makes the steering wheel straighten when you let go. It simply allows the wheels to pivot and not oppose whatever direction the front end wants to go (like a shopping cart). The feature which straightens the wheel is that whenever you turn, the front end lifts slightly, so gravity re-centers the steering. In my cases, the problem wasn't the wheels wanting to go straight, but rather to go in a different direction than I was pulling the car.

I suspect it is due to too much negative caster. The suspension looked OK and it drove fine except for slight rattling on bumps (worn bushings?).

BTW, I towed my 69 Dart with the same tow bar 300 miles with no problems. I have also towed my 65 Newport several times with the same tow bar.

Any thoughts or experiences would be appreciated.