I also drive a CR-V. I have used a Graco Turbobooster, and it worked well with the shape of the seats. I don't know if a 5 year old could buckle a booster without help, but at least the Turbobosoter is narrower, so it's more likely that she could reach the buckle stalk.
The downside to the Graco is that it is not a LATCH-ing booster. That means you'll have to buckle the booster in even when it's empty so that it does not become a projectile in a crash. It's not a huge deal, just one extra step to remember.
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