I have been successful keeping a captive bred Kinyongia tavetana male and female in 30x16x16 cage. I would not go any smaller though especially for a wild caught animal. They are a smaller to medium sized chameleon but very active and need enough room to roam. Being that I hatched out the ones I kept in that size cage they were used to being caged anyway. WC ones should be given plenty of room and a densely planted enclosure.
Out of 12 WC tavetana that I have had since keeping chameleons I only could keep one for any longer period of time which was 6 months. Most of the ones I got came in in bad shape or just did not acclimate. I have had some success with the captive born ones though.
If you need any information on temperatures, humidity, demeanor etc please do not hesitate to ask!!!