I used a piece of PVC pipe to support my handle bar bag. The pipe broke.

To be specific, I used a second stem, in my case an adjustable stem to lower my handlebar bag. The PVC pipe was between that stem and the bracket for the handlebar bag.



Three years later, the PVC pipe sheared in between the bracket on one side and the stem.



On other bikes I had used a piece of metal from a donor handlebar to connect the bar bag bracket to a second stem. But lacking that I tried to use PVC. I was fortunate to be less than two miles from home when it broke.

Good luck. I hope you do not have the same experience I had. In your case, if your trailer separates from the bike, the trailer could travel to places you do not want it to travel too, since much or most of the weight in the trailer would be on wheels.