Vent for extended shower drain

[Seattle38]

Hi all, have a basement bath remodel going on. The following picture illustrates the existing basement bathroom drains, which are labeled. I am moving the shower drain (2") about five feet from its existing location (farther away from the vent), which consequently makes it so the original vent is over 5 feet from the new drain.

What are my options? Use the existing vent? Add a vent closer to the new shower drain and connect to vent stack? or can I use an air admittance valve closer to the new shower drain?

 

[Cacher_Chick]

You are going to have to meet code as a minimum, which will not allow either/any vent to run horizontally below the floor.