Bump stops and anti tramp bars may serve you well. But they are symptom treaters. I have the 4 leaf 4 seater springs with adjustable AVOs. Do this first. The other measures may help against twisting and lateral forces. But the spring itself remains too weak.
Sound advice indeed.
I would be surprised if the torque delivery of a standard plus 4 really merits anti tramp unless you are into really flooring it with racing starts.
