YANBU at all. Our life improved so much for both our children when we did CIO - for bedtime first, then later on naps. Our first DS particularly was absolutely knackered and miserable and gripey all the time. Then we did CIO and got him on a proper nap routine and he was SO much happier, the little dark circles under his eyes went away.
That said, naps are hard for CIO. It's pretty ridiculous for them to cry for longer than they nap! And if you've not good a good nap routine already, it's hard ot know when to put them down. I highly highly recommend the book Precious Little Sleep for lots of advice on all sorts of sleep issues which lays out all the options for you to choose from. It's very realistic and open-minded and not a patented method at all.
Our second, we did CIO for naps AFTER we'd established a rock solid routine of nap timings - 9am, 12pm, 3pm, at the time. She slept brilliantly in the sling for them but was just starting to get way too heavy and I couldn't be jiggling around to white noise for three hours a day with another one to look after! So I was absolutely certain that I was putting her down when she was correctly tired, iyswim. If he goes down at the same time every day already that's fine, or if he naps well in the buggy you could walk him round til you've got a good sense of timings.
It is hard to do CIO with naps in practice, but in principle it can be done and I see no problem with it. You'll get lots of people telling you they never let their babies cry for even a minute ever, but either:
a) They are lying
b) They can't remember from being too sleep-deprived!
c) They had magical unicorn babies
d) They had nothing else to do and spent literally the whole day holding their babies and catering to their every whim (and are also somehow psychic and able to tell what those whims were)
You make sure you've taken care of all their physical needs, give them a cuddle and a story, then leave them to get on with it. At that age, though, I'd be thinking about putting a cuddly toy in the cot with them to play with until they drop off.
Sleep is the #1 priority in our house (theirs and mine!) and I don't care how we get it. Yes, I'm a heartless cow, but I don't think I would have been doing mine any favours to let them not nap.
By the way, DD is now 11 months old and has only just stopped a few weeks ago her "evening yowl", as we call it. Just like yours, a bit of a cry before sleeping through the night and waking up happy as Larry.