what size truck do i need to tow a 26' trailer

Most any F150 with the 7000-7050lb GVWR should be fine.
Either the 5.0 or the EB with the 3.55 gears would be ideal. The 10 sp tranny will put you in the right gear for the situation.
And seriously you TT won't weigh 9000 lbs when loaded. For one there's not enough room inside or in the front storage to load 3300 lbs of stuff. I have a 5th wheel with way way more storage than any 26' TT and even loading all the stuff I don't need I'm at 1500 lbs or so.
My guess is you'll be around 6700-7000 max.