Did some research. kU has 57,117 alumni in KC (Wy, Joco, Platte, Clay, Jack) Mizzou has 25,589. So Yes kU has more in immediate KC metro, BUT...
of those 57,117 all but 12,746 live in kansas (greater KC- Wy.(3,034) and - JoCo (41,337)). Now, I can not find a break down of Mizzou, but all Mizzou would have to have in order to outnumber ku in kcmo (clay, jack, platte) is to have 49.82% of the greater kc alumni live in Mo. That is a safe assumption (probably closer to 80 to 85%) If 90% of Mizzou KC alumni live in Missouri that would be 23,030 which mean we would beat kU in kcmo by over 10,000. (80% is 20,471 a margin just under 8,000. So moral of the story....
If they are gonna put a damn billboard up it better be in Overland Park, Olathe, or Shawnee not Independence.
(I used the kc star one for proper comparison figures).
kU data: University of kansas Office or Institutional Research and Planning Table 2-201 (data as of 12/31/11)
MU data: http://www.missouri.edu/about/mufacts.php