Get the rig loaded as you normally travel and get thee to the scale. I will be surprised if that trailer doesn't weigh something north of 8,000# (never, but never believe "Dry" anything weights!). The biggest problem you probably have and like everyone else here this conjecture until you get back from the scale, but....
Five will get you ten that you are over, probably waaaay over your trucks payload. An 8,000# TT needs to generate at least 1,000#+ of tongue weight. Add in another 100# for the WDH and then start subtracting from your trucks payload (see the sticker on the inside of the door post. You probably have around 1400# of available payload or less if it is a 4X4 or crew cab.
Also.... IMHO: You need to lose the P's. They have no business on a truck that pulls as much trailer as you have. Get a set of E rated LT's (I recommend the Michelin LTX M/S 2's but I digress), weigh your rig and reload as necessary to insure at least 13% TW and I think you will be much happier.
The F-150 Ecco Boost is a great truck but towing 8,000+# with anything less than the Max Payload and towing packages is NOT what they were designed to do. Can you do it? You betcha... but just because you can do something does not mean it is a good idea. :S
Good Luck!
:C