I bought a Gentex GENK-40 auto-dimming mirror off of
ebay for around $70. This worked out perfectly. As you point out, the Sports Pkg already has the compass and outside temp. So, auto-dimming and Homelink is all you need.
First piece of advice, after calling several Toyota dealers who mostly gave bum advice, the way to remove the old mirror is to tap gentley using a rubber mallot from the bottom and the old mirror will slide upward and off the windshield mount.
DO NOT attempt to pry the mirror toward you as several dealerships indicated to do. What appears to be a plastic housing on the stock mirror is actually one piece. Prying will likely shatter your windshield.
If you look under the stock mirror while it's mounted, you will notice a narrow slot on the bottom. There is actually a locking clip that you should use a small screwdriver to disengage. However, I didn't know this until after removal, and, the old mirror came off for me w/o damage. You just need to be gentle.
Second piece of advice, suggest using the power source from the overhead console. It's convenient and relatively easy if you know what to do. First, remove the overhead console. Do this by opening the sun-glasses storage compartment and you'll see a phillips head screw; remove it. Next, the console is held in place by two clips near the front. Simply pull downward with a fair amount of force. In my case, one of the clips came apart (did not break). But, it was simple to reassemble. Next, disconnect the two wire harness plug assemblies and set the overhead console aside. Now, you just need to figure out which wires to connect to. For the Homelink system, use the dome light positive lead (you always want power to the Homelink buttons, even when the ignition is turned off). I don't remember which wire that was (I should have taken pics), but, with a volt meter, this is a relatively simple task to figure out. For the auto-dimming power source, use the positive lead that the outside temp gauge / compass use (that means the power source turns off when you turn off the ignition). Again, a volt meter will tell you which wire that is (if I recall correctly, it was the thickest of the wires going into that plug). For the mirror's negative lead, I used the dome light's negative lead. For splicing into the wires, suggest going to Walmart and buying a pack of the smallest 3M wire splicers (they're in the automotive section near replacement light bulbs); these worked just fine.
One last piece of advice for a nice finished look - The mirror I bought on
ebay, which by the way came out of a Murano, had a wiring harness consisted of 3 loose wires (1.Homelink, 2.Auto-Dim, and 3.Ground). I used the sheathing from an old computer monitor cable to form the jacket over those wires. The results gave a factory appearance. From the computer monitor cable, I cut a length of about 8 inches or so and removed the existing cable from the jacket or sheathing (the outer layer). Using dish soap, I coated the 3 wires from the mirror plug and fed them into the now hollow wire jacket. I must admit, I didn't think the wires would feed all the way through, but, they did. Once the mirror is mounted, you can feed wires through the notch located in the headliner (note, you need to do this before you make your final connections).
I installed mine about a month ago and haven't had any problems with overloading the circuit (i.e., blowing any fuses). The job took about 3 hours, but, most of the time was spent figuring out what you now know. If you are comfortable with wiring 12-volt systems, I think you'd find this to be a relatively easy task. Hope this helps anyone considering to do the same. I've attached two pics of the finished result.
Front View
View from Behind Mirror
Auto Dimming(EC) mirror w/Homelink for 05 Taco
Linear Mode
