I use the evo has a guide scope and I'm in the process of putting this together myself for a widefield setup, just waiting for clear nights.
I have been using that adaptor you linked for filters on my 294 without issues.
I was kind of hoping I wouldn't get vignetting, but looks manageable.
Being relatively new to this hobby,I was more concerned about the image scale at 3.95pixels ,seems to go against all my research so far but I see some fantastic images at this scale and higher.
Hopefully I get outside soon and see how this goes. All part of the fun 👍