Nice use of the entire frame, most(myself included) just cut it-off and use square stock.
That's a seriously long tongue. Do you have any plans to utilize that space? Might be cool to mount a grill, full size spare, generator, etc. up there? Looking good so far. 
In order for a truck bed trailer to track correctly/safely behind the tow vehicle, you usually have to extend the frame quite a bit to get a proper ratio of length for and aft axle center line, if you don't, the trailer will tend to wander behind the tow vehicle.
