Heat Transfer image with white on dark garment

I have a customer that has a very detailed design that they want to put on navy blue shirts. The image has alot of white in it which can not be printed. In order to keep the detail I have told them it needs to be heat transfered but there will be a white border around it. Any suggestion on the best way get this design transfered to a dark shirts? I explained that white shirts would look better with this design, but in case they a stuck on dark shirts any help is appreciated. Here is the design.