I'm putting in a basement bathroom and working through the drain layout. There is a slab already poured so I want to get it right before busting up the concrete. It will be inspected, basically following UPC code (Oregon). This is my first time doing drains and I'm seeking feedback on the plan.
I reworked this a little bit more, and most importantly talked with the inspector. I learned in my city they now allow Air Admittance Valves (aka AAV, studor valve, or cheater valve) so the long vent pipe isn't necessary. I just have to have a louvered cover over it on the wall so it could 1) be replaced if it ever fails and 2) draw air into the drain.
Also per the answer below I couldn't have the shower join the drain pipe before the wet vent so that is solved with this second plan.
The particular backwater valve linked in the answer had some specific installation instructions regarding the 2 foot rule. Thats not in the code anywhere and the inspector I talked to hadn't known of the 2 foot rule, and just said get the valve that doesn't have that in the instructions (since instructions must be followed per the code). I picked up a backwater valve without any mention of the rule but still allowed 2 feet of a straight shot into the valve anyway in this redesign.
I'll amend this post if I have any problem with the inspection, but so far so good.