Depends of what factory hitch you have?
My 2017 F350 come with 3" receiver, so for about $40 I bought 4 ft of 3" square tubing.
Had to do reduction sleeve for 2" ball mount as tubing had weld inside, add safety cables and trailer wire extension.
All together come to less than $100 and my 3000lb boat went behind it just fine.
Your trailer is much heavier, but then you need only 1/2 of stinger I had.
Bottom line, if you can get factory 3" hitch that would fit your truck, you'd be way ahead of any other designs.
I did rough calculation and 3" tubing with 1/4" walls is stronger than combination of 2.5 and 2" stingers for vertical loads and way stronger for horizontal loads.