I had one that just had the 2-inch square receiver instead of the permanent mounted ball like yours. If you could get that, then use a std 2-inch ball mount, it would extend the ball mounting point out from the back of your truck a bit more. Which is what you need. The alternative is buy a trailer with extended tongue, but I think the new 2-inch receiver hitch adapter will fix your problem.
I do not have that T/C and receiver hitch anymore, so not able to give a source to buy what I suggested.
2005 Kenworth Showhauler 45 ft total length
twin screw, 450 hp ISX, 10 speed Ultrashift