AC condensate line re-connect

Took my lavatory drain apart to unclog a hairball, and when I put all the pieces back together, I had leaks..., then I started reading up on connecting AC condensate lines, codes, etc.
The whole plumbing layout did not look right to me, with vertical extensions on the p trap. Each of those additional joints were a leak waiting to happen. I decided to try to fix it right, which is why I'm posting here.
My idea is to do away with the existing rigid AC condensate line and replace it with flexible tubing; I would cut the PVC a few inches from the sheetrock, attach the flexible tubing at the stub, and run it from there to the tailpiece, maintaining a slight grade.
The problem comes in attaching it to the tailpiece. I've found a 1-1/4" fine-thread Lavatory Branch Tailpiece (available at wholesalers?) that solves the problem of attaching the condensate line to the tailpiece, but creates the problem of how to attach the pop-up stopper rod.
Am I missing anything here?
Any help is appreciated. Thanks in advance.

You almost got it.

Have a regular 1-1/4" pop up assembly then right below it, a 1-1/2" branch tailpipe (where your T is located right now) - and you can have your A/C discharge without being in the way of the pop up stopper.

Throw the plastic popup drain away and purchase a brass one. The branch tailpiece will screw into it and you will also have a better drain fitting. The "leak that is waiting to happen" is the one at the left where the trap connects to that extension. The tubing only goes into the trap about a 1/4" so anything that bumps it will pull it apart.

You'll have a lot of water in that assembly...much more than in a normally configured trap. Enough so that some would always be in the arm for your condensate drain line. I wouldn't be surprised if it drained slowly and accumulated crud faster than 'normal'.

Don't know about in the states, but the Canadian code states that any drain or condensate line from a furnace shall be indirectly connected to the drain.

Here it says 'indirectly to the drain SYSTEM" which the lavatory branch tailpiece does.

Thanks to all who replied.
dj2, I tried to configure the 1 1/2" branch tailpiece (where my T was located), but I didn't gain anything. I still had lots of water in my uber-deep p trap, like jadnashua said, and the extra connections required from extensions still posed potential leaks, like hj mentioned. hj, I like the idea of a brass tailpiece, but how do I solve the problem of the branch/ac connection being vertically too low, putting me back in the deep p trap situation?
My solution ended up this way: drilling a hole in the side of the polypropylene (PP) tailpiece, then threading a 3/4" PVC stub in to the PP and sawing it off. Glued the PVC stub to the PP. Hard to find a glue solution for gluing PP because it is designed to resist solvents, and most glues use a solvent base to dissolve the plastic. Found Loctite's Plastic Bonding System, which uses a hexane-based "activator" for step 1, then follows with a cyanoacrylate (superglue) glue. Very strong and provides integrity to support the stiff vinyl tubing. Used silicone to seal all threads for a watertight connection.
I never put much stock in reviews of things that have not withstood a little wear and tear, so this falls in that category. Just wanted to mention how I went about fixing it.