Looking for a Mechanical Engineer for Retail Store Truck

We are about to design one mobile retail store mounted on a truck. One of the targets will hopefully be for clinics around who provide frequent health care services and annual check ups to the schools children in Elementary and Secondary Schools. We want a design where the sides of the store can be opened down and acting as deck with legs sitting on the ground, like stages, and providing additional space. It could be designed by hydraulic, electrical OR made of a light steel to be opened manually but stand weights of the people coming on. The engineer must be able to take care of the electrical plan as well. For this unit, we only have lighting, and for this specific design, some medical equipment with low power consumption like Eye Exam equipment as the most. But we need see what electrical options we could use as per your experience to be silent, clean, cost efficient but sufficient enough to work at least 5 hours off grid, if possible. However, the electrical is not the main issue at this point and will be handled during the process.