Re: '"how far can I push this before it gets silly". A true engineer'
"An Engineer is someone who works with engines/structures"
This is a common misapprehension. "Engineer" derives from the same root semantically as "ingenious", not from "engine". Indeed "engine" drives independently from the same root.
This misapprehension has caused every technician and fitter to be miscalled "engineer", and has thus caused great confusion.
In reality, an engineer typically converts ideas and concepts into specifications of realisable deliverables via processes of planning and design, then passes those specifications to technicians to be implemented.
On the other hand, innovators are obliged to undertake the entire end to end process, specifically because everything from the idea to the implementation is likely to be novel. Consequently, the results will commonly be prototypes, rather than finished products.