Sewer smell and noise from new shower drain, but GC insists he put a P-trap

[WallyWater1]

Ok. So here is my schematic for the vent. To minimize demolition, I want to add the sanitary tee to connect to vent under the shower entrance step, which is right in line with the nearest vent stack, bringing a straight pipe directly into it. The distance from the trap to vent will be 5 feet with 2" piping.

Will this work? Or, do I need to bring the vent pipe's connection into the vent stack higher up?

 

[JG plumbing]

Where is the drain in the scenario you have drawn above?

 

[JG plumbing]

Having not seen this entire arrangement I don't feel comfortable telling to you that this will fix your problem.

Is there a reason you don't have a plumber come fix this?

 

[WallyWater1]

Drain is 5 feet behind the t joint, at the center of the shower. I have the top-down schematic in the opening post.

Plumber is coming out today to fix, so I want to have a good idea on what exactly needs to be done.