Better/safer to have only one w/d bar? Or none?

I'd leave one one.

The forces of a single bar are still mostly inline with the trailer, and your hitch system sees far more eccentric loading during normal turns with both bars hooked up. One bar gives you half WD so it still aids with traction on your steer tires.

I agree with Ben on the bunjee. Had to do that on my Hensley once. Worked fine.