Fire hawk helicopters in Florida use something pretty close to what you are talking about. Give them a call about the software and stc etc. They have them mounted beneath their Fire-hawks. The guys on fires like them. Not much good for precision or production work. They also have a fleet of AS350 which I'm sure they have tried the cameras out on.
The stc floor window is the way to go IMHO or else a good left hand drive conversion. Mirrors are not much good with any line over 25ft unless your checking on the load in forward flight. But the camera would certainly help prior to getting the load to the window. Let us know how it works out