APT writes “Generally I agree with payload being the lowest limit for half ton towing. However, OP has the Harley Davidson model which is also included in your copied noted number 2 which is 5100 pounds. “
That would be a fully loaded trailer provided the tongue weight is no more than 765 lbs."
The problem with that assumption is as the OP found out, they only have 915 lbs of cargo available which if the OP was planning to not add any passengers and gear into the vehicle a 5,100 lb FULLY LOADED TRAILER would be somewhat doable..
However, as the OP found out, adding passengers and gear plus adding the weight of the hitch head and wd there is simply not enough payload to go around for a fully loaded 5100 lb trailer..
Not to mention totally eliminating their choice of trailer which the EMPTY WEIGHT is 5300 lbs 550 lb tongue (pretty light tongue weight to boot)..
Instead, they found out that they would have to look for a trailer when fully loaded is not much more than 3,600 lbs with the passengers and gear loaded in the vehicle..
Although, if the OP used the cargo weight from the yellow sticker, they would not have needed to deduct 150 lbs for driver since that should have already been accounted for.. This would give them 150 lbs more cargo which would be about 1,000 lbs more trailer but that would only be 4,600 lbs loaded, still well short of 5,100 listed in the guide.
But if they calculated via GVWR - Curb weight then driver AND fuel needs to subtracted from the available cargo.
It is far better to error a bit on the lower weight side of a trailer rather to make a huge expensive mistake which ultimately could cost them at least a new tow vehicle..
OP has a nice truck, no doubt, but all that bling adds weight to the vehicle which takes away cargo rather than increasing cargo..
Available cargo weight after deducting passengers and gear supersedes ANYTHING “published” in any generic “towing guide”.
Published towing guides are simply a GUIDE and nothing more since with Ford there are literally thousands of option combinations for the F150 with only a couple of combinations that “add” cargo, the rest all reduce cargo.
There is no way that Ford could publish a complete guide on every single possible option combination which is why they stated at the bottom of the fine print to check the Safety Compliance Label which is on the vehicle.
I realize it is dirt simple to point them to a generic towing guide but by doing so they can easily make wrong assumptions.
That IS why it is better to tell them how to determine towing capacity from the info posted on the vehicles door stickers. The info IS there, folks just need some education on how to arrive at a answer.