Steel Window Header Design stamped with Connecticut Engineer seal

I'm seeking an experienced engineer to with design and calculate specifications for a steel window header in a residential building. I have a 20 Foot Wall in the rear of my house. Expanding a 12 Foot Sliding door to a 18 Foot Sliding door. I have a floor above with 8 foot ceiling, and a storage attic with a gable roof with asphalt shingles. The main floor where the 18 foot patio door is being installed has 7foot 6 Inch ceiling height and about 9 inches between the top of the new sliding door and the joists which are open and exposed as part of the design. The house was built in 1929 and we believe it has a balloon framing structure. The wall is 2x6 Construction and the house is elevated with concrete piers. In the rear directly under this wall are three piers, two on each the far left and Right and one in the center under the door. The wind on the outside of that wall can be somewhat fierce. This needs to be engineered in a way that will not require a crane or any lifting equipment, and a three-man crew can lift. I would prefer LVL wood with Steal plate if possible if possible. if not possible then multiple steal beams that can be installed by three men or a Beam/config that can be constructed in pieces. Any solution will need to be nailed or bolted and not welded.

Key requirements include:
- Detailed design and structural calculations
- Compliance with local building codes and regulations
- Experience with residential steel structures

Ideal skills and experience:
- Structural engineering degree
- Proficiency in design software (e.g., AutoCAD, Revit)
- Strong knowledge of steel construction and residential projects