>>114861666482 from the 80s is a 4wide rescue helicopter that fits a stretcher but as you said it's a tandem rotor. It fits a battery box so it can easily be made shorter. And you could examine the rear door to see if it can be made less tall. And then there is 6691 which is a 4 wide regular rescue helicopter that fits a stretcher via a rear door. But the design is quite boxy and the skids make it wider. See if you can combine design elements from both.
