I actually play with the same mouse. One handed play is tough for sure. I play with a very unique set up myself. I play with the g700 in my right hand, and a razor sabertooth xbox controller in my left hand. What works well for me is to use the analog stick in my left hand for movement/dodging and the keys on the underside of the controller as modifiers (shift and control). Using this set up, I bind 5 of the mouse buttons to 1-5, then I bind weapon skills to 1-5, utility to shift+1-5 and class mechanic to ctrl+1-5.
Using modifier keys like that is a good way to get more actions compressed into fewer keys (I also have combos like ctrl+shift+1 for other actions etc).
What is your current ability? Are you able to move your character while casting skills? Can you quickly dodge if need be?
Power engi might not be too bad, you can certainly do a basic rotation, although the full rotation would be difficult.
Condi ranger could work. The problem is condi ranger uses weapon+utility skills + f1. If you bind 2,3,4,5 to you thumb buttons that will cover the weapon skills. As for utility. The 3 buttons near your pointer finger + mouse wheel left and right could cover the 5 utlitiy. Or if it is comfortable, you could bind one of your pointer finger buttons to shift, and use a modifier key set up.
