I am born and raised on the East Coast of Scotland and have never heard of Camel as a variant of Campbell, nor have I heard of this surname in Scotland. I first heard of Camel as a surname when I was down in the South West of England and heard of it there. Spellings include Camel, Cammell, Camell, Kamel, Kamell, Kamall, Kemell, Kemwal, etc.
You might find this link interesting.