I feel spoilt now I got 4metres by about 9metres. That would be 13' x 29' ish.
But no door apart from some crates. Still the show must go on. The american system for wall thickness in tubing I don't get. I remember the imperial measurement days as an apprentice. But we used fractions of an inch more if I am correct and for sheet metal it was a certain gauge thickness. I think 10 gauge is 1/8th inch thick. I suppose yours is in thousanths of an inch correct?