Wheel Size Question.

It all boils down to What you want your car to be, A race car or a street car. Do you want everything to fit in the factory wheel openings or are you willing to make body mods. Just saying that it is easy to think you are the smartest guy in the room and recommend things when you are not that guy and can't really know what is in his head as to what he expects. People tend to take something simple and turn it into something complex.
Right off the bat you say that YOU would run a 275 MM tire. What aspect ratio? 30,40,50 ? That will determine the tire and rim diameter. And then the offsets and backspacing would be determined on that info.
The farther you get away from the factory set-up the more your info becomes theoretical.
I would try to make it a simple progression from the stock sizing to maybe explain plus sizing is and how that affects the fitment on a stock suspension. How one change makes other changes mandatory for it to work. Domino effect...
Get back on your box. I just posted charts for people to reference for themselves. It is up to them what they do. It is after all their money that will be spent.