Hellobee Boards

I have an older Graco clone (MyRide 65) in a Nissan Versa hatchback. It's not as tiny as either of your cars, but still small compared to a sedan. It fits really well in our car and H was rear-facing until two. We put her behind the passenger seat with LATCH and I wasn't terribly uncomfortable in the driver's seat (we drove to Florida, which is 15 hours from our house).

I have a Toyota Matrix and rear facing only allow one person to sit in the front. I'm not talk but I can't even Fit in the passenger seat if DS is behind me RF. Needless to say we don't use it as our family car! The matrix has bad reviews for this, maybe the Yaris is better?

I have a Honda Fit and just switched from the Chicco Key Fit to the Graco extend2fit. Even on a fairly reclined setting (T doesn't sleep well when his head tips forward) there's SO much more room front to back. Also he stays so much cooler in it. The fabric is mesh and plus it's just roomier. And you can rear face for a very long time.

We have Britax Boulevards and had to FF at 3 years for my tiny LO in the 10th % for height. I think we have the regular model, not click tight but just wanted to mention since your LO is much bigger.
We also have 2 Toyotas and just couldn't get the center seat belt install on either of them. Not sure how the Yards is but you might want a certified tech to help with the installation if the seat you buy doesn't fit behind the driver.