I just made an extension this weekend for my kid's sailboat trailer using a 4 1/2 foot long piece of 2 1/2 square tube slipped into the existing 3" steel.
A new coupler from Home Depot was $13
The steel was $25
I locked the tube in place with a pair of 1/2 inch pins for $6
Should be some steel place around that you can pick it up from!
Now I can slide it back into the existing tube to shorten it up so it fits in my garage better!
