Engineer 12x40 Trailer Frame

I’m ready to move my 12 ft × 40 ft trailer-home project from concept to engineer-stamped drawings and calculations. The layout is largely set, but the structural backbone—the light-gauge steel frame and the continuous precast concrete footing—still needs a seasoned structural engineer’s touch.

Scope
• Frame: 12" × 20' boxed C-channel (14 ga) with 2" × 2" tubing skeleton.
• Footing: continuous precast concrete, tied to the steel chassis.
• Roof: open-beam gambrel with a loft; span and connection logic must marry to the frame you design.

What’s already fixed
• Material: light-gauge steel only (14 ga primary, 20 ga secondary).
• No site plans, electrical, HVAC, or plumbing are required—just the structure.

What still needs your expertise
– Final member sizes, connection details, and weld/bolt schedule.
– Footing geometry and anchorage.
– Calculations that satisfy U.S. trailer (not residential house) loading criteria and whichever ICC/ANSI or state transport codes typically apply.

Deliverables
1. Signed and sealed structural drawings (PDF + DWG) ready for manufacturing.
2. Full calculation package (PDF) showing load paths, deflection checks, and code references.
3. Brief material list keyed to the drawings.

I’m looking for a straightforward, realistic fee—no low-ball offers that balloon later. If you have verifiable U.S. trailer-home experience and work comfortably in software such as AutoCAD, Revit, RISA, or similar, let’s get this framed up.