Honest answer: Diono/Sunshine Kids keeps changing their minds on what degree of bracing is allowed. The way I have it may currently be disallowed by them, so I would go directly to the source to find out how they currently feel about bracing. However I have it installed was allowed at the time I first installed it that way, and I haven't felt the need to change it as a consumer - as a tech I'd recommend always looking at the most current recommendations. You'll also want to verify that there's no airbag interference (in my vehicle, that's only an issue on the passenger side.)
I think the stats I looked at today have 1-2" more in each the second and third rows in your vehicle over mine - something like 1.4 and 1.9" respectively. So you might get a bit more space.
Loading a newborn into the center might be tough. I'd probably aim to do it from the opposite side. Honestly, if you set that seat up and sat in it, it would probably make your life a lot easier. (A lot of that depends on if you're able to work out the three-across situation in the third row, or whether you need to move a car seat to the second row, of course.)
An alternate option might be putting your toddler in the center, and your newborn outboard in something shorter-shelled that puzzles well - a MyRide or a Coccoro for example. I am a big proponent of using a convertible from birth, but lifting a newborn into the center seat with another car seat next to it sounds a bit like torture.
I can take a photo of my current setup (RF Radian behind driver, braced but no AA,) if that helps? If it's warm enough and I have energy when I finish at the office, I could possibly even get it installed with the angle adjuster.