I too added a TruTrak AP to a flying RV-8. (a third hand DFC-250). I have to drill out rivets for the pitch servo bracket in the tail to install that bracket (my RV-8's kit was from 2005). I like the idea of running the pitch server wiring under the left or right gunnel but in my case, I ran it down the tunnel under the seats and floor pan. It was not too difficult and since I already had to have the front seat out and the baggage floor out, I was already 70%.
Including the work for pitot-static, wire harness, server install, head unit install (I did not have a pre-existing hole to re-use), I spent three weekends from start to finish (and no crazy long days).
In addition to gaining an autopilot, I learned a lot about various systems in the airplane. I would definitely do it again.
One suggestion - I recommend putting all the wires into the wire harness even if you are not planning to connect them all up (eg, audio out for alerts, etc.). Just roll up the unused wires and tie-wrap them. Its easier to include those wires now than to add them in later if you decide you want them.