It seems that the developer didn't implement a function for the backspace key. There is no way to obtain a mirror copy of the key. In this matter, you need to use the pre-defined key for deleting characters backwards.
However, you can try to change the key-bindings of your keyboard and replace the '~' key (or any other key) with backspace. To do this, you will need to use the KeyBindingsEditor to change the keys between them. After you created the file with the name DefaultKeyBinding.dict, copy it to the following location :
~/Library/KeyBindings/ where ~ denotes your home directory. You should be able to type with one hand without any problems.