Also, it is a tandem axle. I gather that also has a bearing on things

I have received a pair of tickets a few months ago for my truck and trailer and was given the typical HTA 85.1 tickets.

Based on all the information I have been reading, the only way that this ticket can be validated is if the officer takes a weight of your vehicle and trailer, is this not correct? That would be the only way the trailer can be verified you are over the registered weight of the 2800 kg when pulled behind a personal use pickup truck? Unless there is a GVWR listed higher than that of course.