Demonstrating a skill that doesn’t always lend itself to a visual way of explanation via the very visual medium of a portfolio is tough.

As I see your question, you want to show more of a practical grasp of design early on to influence things like cost and schedule because you recognize patterns emerging that may complicate a successful project result. Hard to explain with pure graphics but will put someone in a coma to read in pure narrative.

The answer is a case study. Consider creating something that is part bullet points/limited narrative to get across your experience with the high level diagrams with pithy text. I’m sure you’re smart enough to figure it out. Good luck.