I'm of the same opinion as Dave (dabar39)

While I appreciate your enthusiasm......From your questions, I do not think that your are in the correct position (experience wise) to be building transport quality products out of Aluminum at this time.

I understand the desire to build trailers etc for one's self, but this is NOT to be done when you are endangering the general motoring public's safety.

Are you ready for the responsibility, either emotional or financial, should one of your trailers fail and cause injury of death.

Did I shock you????

Good. Keep the images of your family and loved ones fresh in your mind while you decide whether to do this or not.

The life that you endanger, may not be your own.

My apologies for being all Gloom 'n' Doom on this topic......This is just no place for beginners.