I think a Flail Mower may be a great choice, some can also be offset to stick out on one side further. A 8' RC is to big for your machine I think.
Here is a 73": Flail Mower, Caroni, Flail Mowers, Caroni Flail Mower | Agri Supply, 30837
There are many other choices if you Google "flail mowers"
Here is a 73": Flail Mower, Caroni, Flail Mowers, Caroni Flail Mower | Agri Supply, 30837
There are many other choices if you Google "flail mowers"