I've got one I am planning on extending, too. Haven't decided yet how much to add to the cab and how much to the bed. Anxiously awaiting what you will do. I figured I'd cut the roll bar angles from the hoop and add horizontal 3" tubing to connect. In your case, that would be about 18 inches. I was wondering how the frame would hold up with the extra length and if it needed any extra support. Thanks for sharing this adventure.
I thought about this as well, but the angle change I think is going to hit the wheel well housing, not sure though... again, this is all been thought over and over and drawn in my head.
Although I am a very detail oriented and can see on paper in my head, it isn't until it is sitting in front of you in steel that you appreciate what is there and how it actually looks.
Last night I got the extensions drilled out and edges ground down for good penetrating welds.
I plan on sleeving the frame, butt welding the joint, and plug welding as well... then fish plating the inside... not sure if I need the fish plate on the outside as well or not... wanted more of a clean look if you looked underneath, but I am not going to sacrifice any strength.
As for more support, the bed will certainly require it... I plan on using the rear most cab support now for the bed... and putting a new one on the extension piece to support the cab.
I will take more pictures when I get a chance, but unfortunately posting them doesn't work for me on my phone... so updates are going to be a lot further and far between as I can only update them when I get on a computer.
cb