I cannot stress enough PiT, Yankee, and Sawx's statements: no other regions should be affected by these reforms. If regions are changed/merged,
it's by their expressed, constitutional consent and only for the purposes of increasing activity.
An easy solution, however, which would basically be constitutional as far as I know, would be to set up a joint government for the two regions. Technically, you'd be living in either the Pacific or Midwest and they'd each vote for a Senator but the regional government would be united.
Now, I like this a lot. They elect one governor and assembly, but still elect different Senators. And maybe the assembly members can be different, too; perhaps 2-3 from the Pacific sub-region and 2-3 from the Midwest sub-region.
I hope a name won't be the death of a plan like this. If "the West" isn't good enough, how about: The Great West, the Pacific and the Prairies[or Plains], the Not-East, Leipistan, New New England, New New Mexico, Frontier, Frontieria, Lewis, Clark, Sacagawea, Adams, Jefferson, Lincoln, Reagan, Clinton, Roosevelt, Obama, Bush, Coolidge, Paul, Marx, West-Of-East-Places, Northwest & Southwest, Pacific & Midwest, West Atlasia...
...that should get the ball rolling, hopefully it doesn't knock anyone over in the process...