My last trailer purchase the salesman and the service writer tried to tell me what size bars I needed. I asked them to weigh the tongue and they replied that they didn't have a scale. I replied "then you don't know what the h*** you are doing". This created quite the debate and the lecture about how long they had been doing this, yada, yada, yada.
We took the trailer to a scale, weighed the tongue and guess what. They didn't know what the h*** they were doing and had to eat crow. The tongue weight was 500 lbs more than their years of knowledge told them.