My brain has been flying on this fusion engine... I am really digging the hybrid dual mode concept. Basically, a fusion thermal rocket combined with a pulsed plasma rocket. I'm looking at creating fusion pellet fuel tanks (the engine has small fusion pellet tanks built in as well), and a support module that's a truss structure of some sort. The pellet tanks will have built-in heat radiators to keep the pellets cool and to shed some of the engine's waste heat. Here's where I'm going with it: