Wow that is a interesting but VERY depressing tool. I played around with it a bit and I put the numbers in for my truck and let it run using different safety margins
For 20% safety margin and 15% Trailer tongue weight percentage override it said:
Maximum Trailer Weight was 4,667 lb (This is the maximum trailer weight based on the most restrictive tow vehicle ratings provided (tongue weight rating at 15% of trailer weight))
Maximum Trailer Weight with Margin was 3,733 lb (This is the maximum trailer weight based on the most restrictive tow vehicle ratings provided, reduced by a safety margin of 20%)
For 15% safety margin and 12% Trailer tongue weight percentage override it said:
Maximum Trailer Weight was 5,833 lb (This is the maximum trailer weight based on the most restrictive tow vehicle ratings provided (tongue weight rating at 15% of trailer weight))
Maximum Trailer Weight with Margin was 4,958 lb (This is the maximum trailer weight based on the most restrictive tow vehicle ratings provided, reduced by a safety margin of 20%)
So if I use the recommended 20% safety margin it says that I can only tow a 3,733 lb trailer based upon my limited tongue wt capacity. :(
I had been looking at a used 2017 Rockwood 2109S trailer that I saw on line. The photo of the door sticker says the trailer weighs (empty) 3924 lbs, can carry no more than 1273 lbs of cargo and is 21 ft long. I guess that makes the trailers GTW equal 5197. The brochure says the dry tongue wt is 415 lb, not that means much. So If I follow these guidelines, even this trailer is beyond my truck. This is very depressing. Am I reading this correctly?