Good engineering generally relies on good starting parameters. Good starting parameters rely on imagination and perspective.
VB - I think I am enrolled in your class professor.
Does this aircraft have any use?
We seem to all agree the above is not worthwhile but I keep coming back to it.
This reminds me of a example from engineering school. A classmate was visited by a traveling salesman trying to keep afloat a home insulation business.
The newly married student had recently purchased a turn of the (20th) century uninsulated home. He pulled out heating oil receipts and did the math showing that it would take nearly fifty years to pay for the insulation the salesman was selling and he sent the sales man packing.
However, in his engineering mind he knew that the improved comfort and economy was a good thing, he just could not prove nor justify it.
Within two years the cost of heating oil was rising and soon was well above the ten cents a gallon used in the example. It is very likely that the house survived the Detroit riots and it may be still standing this day.
Conclusion: If the results are questionable so are the engineering assumptions and vice versa.
PS: I think there may be a market for a tail wheel conversion on a C-172. There is one available for my sons 175 but as you say it’s cost benefit numbers do not work out.
In your example, the engineering student forgot what the house was actually for (er...living in), but in his defense, maybe he had to live in an uncomfortable, drafty house for a few years to expand his mind.
Or he didn't realize he could get quotes and very likely beat the salesman's price. Or do the easy parts, like the attic, himself. Or figure out what parts would be most cost-effective (begin with the most leaky windows).
Bottom line: his starting assumptions gave him incorrect results. Sometimes you have to step way, way back and ask yourself, "What was the goal, again?"
"Oh, that's right! To fly cheaply!"