I put a Ursus Jumbo on my tandem. I don't have heavy bags on my tandem, but I do get a three- year old out of the trailer and he likes to wiggle/bump the tandem on his way out. Also my stoker is six so he increases the chance of my tandem tipping over instead of reducing it.
I would see if you could get a Ursus Jumbo to work on your Cannondale.
