Shortening rear end and backing brace?

Thanks for the info.
I have the bar and the spacers already, as well as an empty center section to pass the bar through to ensure the flanges stay straight.

It's more the welding sequence, and type MIG or Stick for them both.
Also the design style/configuration for the strong back.

I have seen them on the internet made from square tubing, pipe, and flat bar with small spacers.
I can make any of them, but want to know which is best?
It doesn't need to be easiest, as I am in no rush, and want to make it right.

I like the square tubing look the best, but again I just want it correct/best.

thanks, again