Lets see, 3 Regional Senate seats, 5 At-Large. Nope, no imbalance against the regions there.
We could do two senate seats from each regional. With five at large we would then have 11 senators. I suppose we could just get rid of the Vice-Presidency then as well.
Or simply make the Vice President a Senator as well...
Though, 12 Senators is quite a bit. In fact, I find 10 to be quite a bit already.
Reduce the Senate to 6 members!
Or better yet
Each region elects it's own senator by whatever means it wishes
The SoFE and RG draw up 3 electoral districts based on STV that elect 1 senator each
ad 4 at-large Senators.