How to develop experiment to justify construction of a prototype system?
What would be a good approach that justifies also the construction of my real system?


I don't have a crystal ball, so I can't say anything other than: in some fields, in addition to showing that your approach works well in a simulated environment, it is a really good idea to also show that your approach works well in practice.

If your peers value such "real world" results, then you don't need to justify it any further than that.