If you look at the canopy of any tree, that is about the spread of the root system. Could you visit a specialist tree nursery? They're usually very knowledgeable and you'd see mature trees for yourself, to check the spread and find out about a suitable tree.

how about an acre shrub rather than a tree as they get quit big .

What's the size of the planter? Camphor trees grow up to 100 ft so not surprising that it is trying to break out. Unless you're able to do some bonsai root pruning, I wouldn't expect to keep anything classed as a tree for more than 3-4 years in a planter (I'm already feeling guilty about Magnolia 'Susan' in her first year in a deep pot)