Most camellias can take quite a bit of sun if they are kept adequately watered. The citrus that may best fit that size area would be some type of a satsuma orange. Shade however is going to dramatically reduce productivity on citrus. I think I'd suggest putting the citrus in sun and the camellia in bright shade. See Monrovia's online plant search feature and type in camellia to get a listing of varieties from which you can get their size and other characteristics.
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