Here's one way of doing it:




but this has been done poorly I think it looks like the roof line is too low. Using 2 door sedan doors would be a better aproach in my opinion and I would love to see it done.

Another aproach I've seen which is more ugly is cutting the bulkhead which holds the rear window out and reversing it. Makes a big bubble out of it instead of being concave and probably gives you about 10cm extra space.

Yet another choice would be to go extended cab. I think this could look the best of the three options if done right. Here's an example which needs to loose the widebody flares: