Darnit! Classic old datasheet trickery. 
I have now seen the newest datasheet I believe...
https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST_BNO055_DS000_14.pdf
Hmm, well this changes things.
I am now going to change from fusion mode to use just the accelerometer and the gyroscope. Hopefully then I can use the 16g and the 2000 degrees/sec config.
Thanks for the patience.