Ok, now I've been reading this thread going "those poor suckers" for a couple of days, until I realized that I'm in a very similar situation. On the way to one of the home planets is what looks like will be a nearly impenetrable world. Here are the a couple of the numerous goodies that are at this Mark III world.
AI Eye x1
Ion Cannon IIx1
Ion Cannon IIIx1
MARK III SPIRE SHIELD SPHERE GUARD POST x2
4x other guard posts.
I haven't even begun to approach this world yet, but it is in the way of the home planet, and has the last core A-shield generator that would not be way out of my way, so I have to take it. I can find no conceivable way. Those Mark III spire guardians have 336,000,000 health. There's always a direct kill of the Eye, but it'd take AGES with all the defenses on this planet. Any advice? I don't even know where to start here. (This is my 1st game btw)