Hopefully they'll approve you fabbing up what you need. You can throw 2x4's in that window for $2 each, but an assembled scissors truss is not coming in.
Agreed.
I had to convert a new construction 2 story house with a 2nd floor tray ceiling in the master bedroom and bath to a vaulted ceiling (first time build, a new model) using scissor trusses. Management pee'd all over the tray ceiling they had spec'd first time they walked thru the unit. Roof was on and shingled.
I had the truss designer design a two piece scissor truss with the vault configuration management liked. The design used the same web arrangements as the prior truss but the scissor truss was two pieces. We took out a triple window and brought the truss halves in and sistered them to the existing trusses and nailed per detail along the overlapping webs. There was a plywood splice detail to marry the two trusses together. Once all were in place and nailed off properly, several hours with a sawzall and all of the old tray roof detail was gone leaving the now vaulted roof in place.
Looked like hell but we had the "repair" detail with red stamps for the inspector. When the inspector walked in the house I handed him the truss drawings and stamped details and said you are going to want to see this...
As a different thought, my prior garage used attic trusses similar to yours. My garage had dormers for the attic. There were several identical attic trusses ganged together to form a girder truss. Then conventional in-fill framing was done between the girders. I had (2) dormers that were 8' wide and they had 3-ply girders flanking the dormer and (1) dormer that was 12' wide with 4-ply girders. My shop was 28' deep clear span. The wall studs below all stacked on the girders. Perhaps you could cut the nails on existing trusses and slide them over to mate with other trusses and form girder trusses followed by in-fill framing. Your roof sheathing nailing would be compromised so not sure how you would cope with that.