I’m not exactly sure, but you have to remember that aluminum square tubing/angle is more brittle than steel and is prone to cracking(especially spider web cracking) at stress points. Where steel is more maluable, if you will, and flexes more with stress.
An example would be taking a piece of angle and bending it: Even with some mild heat at a certain point aluminum will crack. Steel will keep on bending!
I would have it done at a aluminum welding shop and have them reinforce the pivot hole and pin hole with a sleeve welded in, and a squarebacker welded around those on the tops and bottoms of the tounge. You can never be too sturdy in my opinion! I hope this all makes sense!