The previous owner of my house installed the bathroom diy. A plumber told me it was not to code so I tore it out. I’ve read that the fixtures need to be within 5’ of the air vent. I’m trying to determine based on this shotgun layout if I can depend solely on the main stack being vented or if I need to tie into the air vent that is odly placed in front of the main stack. In the 3rd photo you can see that the air vent is close enough that I could tie the sink or toilet to it if the main stack did not work.