Aerospace/mechanical engineer needed to design a drone structure

I'm looking for a mechanical or aerospace/aeronautical engineer to optimize or redesign an internal structure of a theoretical aircraft/drone given a draft of internal structure and an external structure. In the front rotors there will be a maximum force of on each rotor and in the rear rotor the maximum force applied would be double than each front rotor. The overall weight should be 40-50kgs and should be able to carry under the belly 250kgs and around 120 Kgs more distributed on the rest of the structure. The materials used should be carbon fiber tubes and rods and mostly alluminium structures. To be noted that the external structure should be connected too. The expected output should be a file .obj or CAD with the composed structure; all the parts should be clear and should be able to be seen divided if required. If possible , also having the drawings of the whole structure and of the divided parts in pdf would be great. Please see in the google drive folder the attached files (internal and eternal structures in both original blender version and exported .obj file). To point out one thing in case there are problems with the scale while opening the files: the diameter of the "holes" in the external model where the front rotors are is 167cm. (so approximately, the surface occupied by the model should be around 4,5 x 4 meters or slightly more). Please make your offer based on the budget you would need for the job. Files: https://drive.google.com/drive/folders/10Vtf2qgsxyMVPRUZ5NX-o8zvQKZoIhjE?usp=sharing