Rittz:
Just like BA does it. But, last night I was looking at the stars and in the constellation Rittziopia the stars were aligned just right to indicate that Rittz needs some ideas and help. So here I are.
I am not sure how this would work, but by working with the truss supplier, could you do the following? Two vertical trusses, 10' wide and 16' high. This gable end truss would have its bottom chord at 16' elev. (the door head), so it would also have 2' high heels out at the eaves. This certainly would be a crazy rigid frame truss system, might be osb or plywd. sheathed both sides. It doesn’t have much roof load on it, but must interact with the roof diaphragm, and take wind loads perpendicular to its plane, as well as those from the whole bldg. which end up in its plane, plus the door loads. It would require pretty husky chord members in both the vert. truss and the gable truss at the door jamb lines. And, it would require some sort of hold down hardware out at the 2' deep heels, 18' long hold down rods from the found. to the top chord.
Alternatively, make the two vert. trusses 10' wide, and 18' high at the eves and about 20.5' high at the door jamb line. The jamb chord on these vert. trusses would have 2 or 3-2x6s (or whatever) cut short at 16' elev. to act as a bearing seat for the door header/gable truss which would be 40' long, btwn. these two vert. truss bearing seats. At the roof plane, you might use steel strapping for continuity btwn. the trusses at the door jamb line; or you might hold the top/sloped chords down, 2 or 3(1.5") so you can install these 2 or 3 added, laminated, top chord members for continuity.
Thicken and reinforce the edges of your approach (apron) slabs. Also, form a nice radius on its two outer corners, or the first time they drive a combine or tractor in there, they will break (crack) a 2 or 3' by 45̊ corner off those aprons.