Under the IPC & IRC the maximum length of a fixture arm can be computed by dividing the diameter of the drain by the pitch. If an 1-1/2" line is installed with the code standard 1/4" per foot pitch the maximum lenght would be 1.5 / .25 = 6ft but in this instance the line has a 1/2" pitch so the maximum allowable length would be 1.5 / .5 = 3'. (The bottom of the drain line at the trap weir may not be higher than the top of the line at the vent opening). Both the configurations illustrated above would not pass code for a number of reasons. The simple solution would be to remove the drum trap & extend the length of the tub drain tailpiece. Code will allow up to 24" vertical drop from the tub drain opening to the water level in the trap. Attach a P-trap and run the line with a 1/4" per foot pitch. A wye can be installed on the drain line with the side input angling downstream. You can then put a street 1/8bend on the wye side opening input, which would turn the side opening vertical and attach an AAV where the base of the AAV is 4" above the drain line. REF-IPC 917.4 Location. The air admittance valve shall be located a minimum of 4 inches (102 mm) above the horizontal branch drain or fixture drain being vented The air admittance valve shall be located within the maximum developed length permitted for the vent. The air admittance valve shall be installed a minimum of 6 inches (152 mm) above insulation materials.

Thanks for the responses! After posting this I did go to our local plumbing supply store. They quoted me about $640 for all the parts in ORB finish, Which honestly is a little more than I was wanting to spend, but might be the best I can find. WD - I chose this type of sink because the bathroom is a 3.5 x 9 room under a stairwell. Because of a cold air return and the layout of the space the sink is mounted where there's not a lot of room in front of it (picture below). I thought putting a vanity might clutter the space more and make it seem smaller. Kudz - I think I'll want to use a tradition P trap instead of the bottle. As fun is the plumbing code is I'm not sure I care to pick through it for bottle traps haha! I am attempting the look in the second picture (just different finish).

Sawzall that pipe about 1 1/2" in front of the coupling. Prime and glue a new coupling, pipe, adapter, and trap.

It should be possible to reconfigure that to have the P-trap in the normal position and reduce much of the unnecessary, extra piping, including getting rid of that gawd-awful, corrugated horizontal pipe. I can't easily explain the solution, but it starts with moving the P-trap and re-orienting the tee. If you have a friend who has any plumbing skills they should be able to uncomplicate this for you. And it will work better. Finally, how high are you raising that AAV? If it's allowed to use an AAV in your locale, it's required to be at least 6" above the "flood level" of the fixture, which is the top rim of the sink.