I've done it. On a smoothed out Streetrod type of build, when I worked in somebody else's shop. Please dont do it. Because of the side profile ( the cowl at rocker height is a lot farther in than it is a the beltline heght ), you'll end up with doors that hang down like a wounded seagul's wings when they are open, Or you will loose a lot of interior space ( in a car that doesnt have any interior space to loose...) If I remember right, I suicided the doors. Which made it a lot better. But then the hinges were still in the way of the seating area....
I put a set on my tudor and it was quite a bit of work. My old hinges were beat up and I figured it would be easier to put the hiddend one in. In hindsight I would have kept the originals.
So if I do hidden hinges on a steel car, most loudmouth cruise night HAMB experts will stand around babbling "it's a glass car, you can tell on account of the hidden hinges"? Thats some serious motivation right there...