I bound Q/E to rotate camera left/right, and right-click to "toggle rotate camera". This way I could rotate by holding down RMB. Worked alright for me. The only downside was if my character was moving, the first right-click wouldn't toggle camera rotation right away - it had to cancel character movement first. Then right-click again and hold to rotate.

"We make our choices and take what comes and the rest is void."