Thanks for the name suggestions, not bad at all!
Well i'm no expert on matter/antimatter

but i guess it depends on the mass of the ISV? Lets assume its really light

Also the engines are only used for braking and then acceleration on the way back. A giant sail is used aswell.
Then again, i do tend to agree with you, these ships go at 0,7 lightspeed, my guess is the speed is a bit too fast to make it plausible, even with antimatter engines. But if not it would become a complete different story, space is just so damn big!