Okay, my heads full of these numbers can someone help:

GVWR - Total amount of weight the vehicle, contents and trailer/contents I believe right?
Tonque weight - Maximum on the hitch right?
Payload - Maximum IN the truck right? Does this include the hitch weight too?
Towing limits - Maximum towable right?


So, here's my question and the math problem:

Data from Trailer:
I'm looking at a "Trail-Lite" 30 foot trailer with slide-out (8304S) to tow that has a dry weight of 4,470 pounds and a GVWR of 5,990 pounds. It has a hitch weight of 390 pounds dry. In addition to this I will be having people in the truck and of course equipment in both the trailer and the bed of the truck.

Data from Truck:
My vehicle is an F150 Supercrew Lariat 4x4 with a 5.4L, 3.55LS, 17" wheels and Towing package. According to Ford my towing capacity is 7,100lbs and my payload is 1,640lbs (I can't seem to find a hitch weight limit - but it reasons its less than 1,640lbs). I believe my truck weighs 5,010 pounds and (I think) has a GVWR of 12,500lbs.


My math figures the following - please help if I'm wrong:
The trailer can be loaded with 1,520lbs of equipment making total trailer weight 5,990 pounds. The truck can then be loaded with 1,115lbs of cargo & passengers (the 1640lbs less my estimated wet tongue weight of 525lbs). This would bring my total loaded weight, trailer and cargo to 7,105lbs making my total vehicle/trailer/cargo at 12,115lbs.

This seems perfect - a 30.5' trailer with a slide-out and 2,635lbs of passengers/cargo all safely within my factory limits (does not take into account the aftermarket power I'm adding for easier towing).


The problem I have with this calculation is this; what if the figures were as follows:
7,100 Trailer Weight (Within spec)
600 Tongue Weight (est)
1,040 Truck Cargo (1640 less estimated tounge weight)
5,010 Truck Weight
------------
13,750lbs - this is over my estimated 12,500GVWR by 1,250 pounds


Is the 1,640lbs of Cargo weight independent of the 7,100 Towing capability? Or do I have to remain under all three numbers - the GVWR, the Towing rating and the cargo rating (this would seem to make since and then my math and the Trailer I'm looking at work fine).


Thank you for your help,
Todd
2002 F150 SuperCrew Lariat 4x4
Raider Black on Silver w/Grey Leather
5.4L; 3.55LS; 17" wheels, Skid Plates, Towing package
Chrome Steps, Factory Bed-Liner and Bed extender
Entertainment Package & Heated Bucket seats.
(Coming Soon) Chip Tuner, MAS kit and Cat-back Exhaust kit