Custom Cell Format In Which Space Follows Thousands Place

I am trying to write a custom cell format that would allow me to replace the comma with a space after the thousand's place. Therefore, 1 million would look like: 1 000 000 instead of 1,000,000. I do NOT want to change my regional settings to accomplish this.

When I write ### ### ### it accomplishes this, however, there is one small glitch. When you apply an "underline" you get the following result:

_1
_10
_100
_1 000
_10 000
_100 000
1 000 000
10 000 000
100 000 000

The underline does not lineup evenly with the "ones" digit until we reach 1 million. I want to write a universal format in which the underline lines up evenly regardless of the number.