SAP_CORBU Theme modification

Hello,

We are implementing ESS\MSS on ECC EHP6 system with portal 7.3.   We are interested in using the SAP_CORBU theme either for Portal, ECC WD4A applications, or both (ideally). 

I have seen the SAP note 1681640 that States the following:

Theme Editing:
You cannot modify SAP CORBU using the theme editor.

But if we just want to change the Logo in the portal or make very minor changes, is there a way to do it? The theme does not show up in the Theme Editor tool?

I don’t see the point of making this theme available for the portal if we are not even able to copy and modify it according to our needs (at least the logo). 

Any alternative solutions or suggestions would be appreciated.

Thanks,
Harman