What head unit are you using to record the power output and other ride data?

You can (probably, depending on head unit) hit the LAP button at key points to break your data up. You said you did a 65 mile ride but the first 10 miles were "the approach" and the last 15 were similar, it's the "middle" 40 miles that you were there for. So you hit lap after 10 miles when the "real" ride begins, and again at 50 when it ends. Now you have metrics for the approach, the ride, and the exit.

Have you found your FTP yet? Once you have that, the intensity factor (IF) for a ride is a great measure of intensity. Normalized power (NP) does a better job than average power of describing how much effort was involved. And total work done.