In yuh Pwefm!

Hello everyone. I'm interested in increasing the range of me 302 Cruiser. I have twin Mercruiser 5.7L sterndrives but my range is limited. I cruise in teh Caribbean and often have to hunt for fuel. Have any of you installed additinal fuel storage on your boats? If so, where have you done so, or what haveyou done? I'm looking for an additional 100 gallons storage. Any ideas? Thanks, Roger