From another post, I remember that you can use the 1242 as a mesh ap, but you have to purchase a license for each ap. Then you can run the mesh code on the WLC. I don't know if WCS will really help you so much since ou only have one controller and it is for open guest access. The fibre/media converter can plug into your rap and the other ap's can act as a map.
You might be able to use the 1242 as an LWAP and other aps as a WGB. Might be cheaper.
-Scott
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