As someone that did the CP ride, I should point out that a really hard group ride isn't really beneficial if you get shelled when they go really hard. As a solo rider it becomes (like it became for me) a regular training ride, 12 mph toodling around, taking a picture or two of the area, trying not to get lost.

There are some other slightly less intense groups out there. I remember a couple/few years ago riding with Celo Pacifica? out of Oceanside, they seemed like a good friendly bunch. Wed there was a super long ride listed in the Cyclovets site (I did it once), an all day affair.

Also, yoga isn't necessarily bad, it just won't help your cycling as much as doing some more training (unless your 2 days a week are very long days initially and race days later). Of course if you have a favorite yoga instructor or some other ulterior motive for attending, more power to you. Life isn't just about cycling.

Finally, keep in mind that 30 min on a trainer at night isn't necessarily a waste of a ride. I found that short recovery/warmup rides help me a lot, so I'll do 30 min on a Sat before a Sunday race, loosen up my legs, etc. A lot of my rides used to be under an hour long, on the trainer, low effort. It could be a short spin right when you get home, just before you leave for work, etc.