I just had an idea. I don't even know if I like it, I'll throw it out there for the community to bash it.
What if there was a fairly substantial price discount for people who's capital ships have been established in-RP? Instead of powertrading for two weeks, lolling about in the capital ship for a few months, then writing an RP, if it was already written before hand, a discount could be applied to capital ship armour, or something.
I suppose we'd need a committee to discuss RP stories and such. Kind of like a lower-tier special-RP request group.
Of course, if the person who wants their capital ship has no desire to establish it in RP, they can pay full price.