Welcome to NERD! We love your creative concept and the idea of utilising stock images, enhancing them and mixing them up in this way. It is right up our street.
Here are a couple of examples where we have done so for previous projects as mentioned in my notes to you.
We started by selecting and prepping the stock elements, placing them into the environment and giving it all a sense of depth and space, we moved the camera and added transitional moments instead of just cuts and even added atmospheric animation too (like smoke, dust secs etc). It really was a huge success and we have used this technique with so many different styles including drawn, illustration, live action and stills.
This approach would work really well and as we have done it so many times already here we can apply all our learnings, tricks of the trade and enhancements that we have gathered over the years. That way we can make cost savings where needed and spend the resource where we see it- on screen! We have a director that specialises in this style & technique so would be getting him on board. You would love collaborating with him as he likes to enhance and push the visuals as much as possible.