As you're likely aware, cutting beyond the 45° limit of the saw can be challenging. It's necessary to think more vertically than usual.
Consider to build a fence that includes a 90° bracket along the entire length (or as needed to provide stiffness) that will permit you to place the angle as desired:
Blade represented in red, circular saw plate is yellow, ...
First and foremost, please note this warning from the manual:
Fitting of other purpose or different sized blades will void the warranty.
Needless to say, you are doing this at your own risk.
With the above out of the way, I have run all the tests that I needed: the blade is fixed and has no play (which suggests that the harbour nut is fully threaded as ...