Custom fitting speakers

How much trouble is it for installers to custom fit 6x9" deep basket speakers into a 5.5" shallow opening? Im planning on putting 4 Alpine 6x9 Type R's into a vehicle with smaller brackets. I am good at building things and have audio experience, would it be possible for me to do it and would I even want to try? How can I increase space for the basket and still acheive a factory look?

Well based on trouble I know locally, it is $100 per hour of custom install, versus 70 per pair of speakers installed