Re: Towing with my F150
I missed the info on the 5 speed, so I'll revise my comments somewhat.
While it is true that many trucks with manual transmissions are rated to tow a great deal less than one with an automatic, I doubt very much that you will have problems with your rig.
Your boat probably weighs about 800 pounds, the motor probably weighs about 250 pounds and the trailer probably weighs about 500 pounds. That's a total of 1,550 pounds empty. With 12 gallons of gas and a few things thrown in the boat, I doubt you'd break a total weight of 1,800 pounds.
This sort of load isn't going to break your truck, nor slow it down much. The only area that I would advise caution on, is in starting from a dead stop. This is especially true on a grade. You have plenty of engine, so you need to mate the clutch and pressure plates evenly and smoothly. You should not need to slip the clutch so dont, because that's what burns a clutch up in short order.
Most manufacturers are well known for under-rating their manual transmission vehicles, and the clutch issue is one reason why. I believe that they also do it, because most manual tranny equipped trucks don't have transmission coolers installed - factory or otherwise. Since heat is the other big cause of transmission failure, its easier to under-rate the truck than to try to educate people on proper treatment of the vehicle.
One of the things that will give you a little better insight as to the true capacity of the truck, is to compare the tow rating posted on the spec tag in the door jam, with the combined gross vehicle weight ratiing and the empty weight of the truck. With manual tranny equipped trucks, there is sometimes a big gap between the empty weight plus the tow rating v. the CGWR. Since your truck is rated to tow up to 8,000 lbs with an auto tranny, frame strength, stiffness, etc. are not going to be limiting factors.
Frankly, I wouldn't worry about your setup. If you think about it, how many times have you seen someone towing a rig that is very similar to yours in terms of weight, with a 30 year old Toyota or S10 with a manual trans and a 4 banger in it? As I said before, I had a boat, motor, trailer combination that was probably very similar to yours in weight, and I towed it with a compact pickup that had a 4 speed and a 1.9L engine. I did it for years and it worked fine. I also didn't break anything doing this.
I don't think you will either.