I'm not sure if there is any smartass white on white text in this question but I'll take it on face value and give the best answer I can.
Nice punch

A simple solution would be to add a sleeve to the tack end of your existing boom to get the extra length.
My current boom is aluminum with a rectangular section. Finding a sleeve and an extension that matches is a challenge I don't want to even consider. It's probably cheaper to buy a new boom length in aluminum.
I found that there is carbon tube and carbon tube. Some are uni-directional fibres along the length of the tube, some are mandrel wrapped, some have extra layers on top. Quite the choice!
Thanks for the info so far. Good food for thought.