Rewards are on the blockchain level though so there is nothing I can do about that.

Yeah, I understand the "private-community-reward-pool" dynamic.

I'm only concerned about visibility.

I could add features like browsing articles and posting, and the investors will never see their posts hidden on steemfiles.com.

Sign me up.

I'm pretty sure you can copy the steemit code (for free) and modify it to ignore rep and blacklists.