Civil Engineer Letter for Roof Load

I need a letter from a licensed Civil Engineer to satisfy county requirements.

Project Details:
- 6 trailers with 26 ga. metal roofs over asphalt shingles
- Roof supported by 2 x 10 rafters on 2 x 4 walls

The letter should include:
- Material types and dimensions
- Roof load calculations
- Overall structural stability

I can provide clear pictures of the trailers and new roofs, but I only have pictures, not blueprints or documentation.

Ideal Skills and Experience:
- Licensed civil engineer
- Experience with structural load assessments
- Familiarity with trailer and roofing structures