Currently I have developed a craft with a 3 launch stack with 4 modules including from back to front a cryogenic RP-1/LOX first stage to begin the Trans-Venus injection burn, a service module with a hypergolic fuel supply which also housed the majority of the electrical system, an inflatable habitation module based on Bigelow Aerospace's Sundancer, and finally a Dragon V2 for the Earth Return Vehicle. This is designed to support 2 people for a 590 day trajectory that was produced by JPL, utilizing a rocket assisted gravity slingshot around both Venus and Mars and then finally back to Earth. In addition, I was thinking that the craft itself should always need to keep its engine facing the sun so that a water layer could be kept between the astronauts and the solar radiation without needing to completely surround the ship. I'm working on a CAD model that I can post when it's done. Thanks for the feedback guys.