I have strong background in aircraft design. I have practiced these kind of projects in my carrier. I know the design requirements, UAVs possible configuration, existing similar models with their detailed specifications, and the overall design procedure.
1. For this project, at first, the configuration should be selected. This is critical, because it will define the future specifications.
2. The vehicle weights, based on it mission is estimated. How much would be the empty weight, the take-off weight, and the fuel weight. The fuel will be computed according to the flight mission.
3. The wing area and the required thrust will be used using matching diagram
4. Tails, if applicable, would be sized according to longitudinal and lateral stability requirements.
5. A CAD model containing the external surfaces, internal structures, and major equipment would be created.
6. Preliminary CFD Analysis would be carried out.
If you are interested, I can send my previous jobs on aircraft design.
Regarding my skill, I am pretty familiar with tools required for design of an aircraft.
I know that my offer is higher than your maximum estimated budget, but actually I know how much is required.