We bought our Tundra AC right before our daughter was born. The infant seat fit fine in the middle and allows both seats to be pushed all the way back, but you can't recline them all the way. We drove from FL to OBX with her when she was 6 months and nobody complained, we even had a 60lb lab back there with her.
She's now 2 and sits in a convertible seat. She still sits in the middle mostly but on occasion we put her behind the passenger seat. With her in the middle my wife can recline all the way to nap. I've tested the same seat forward facing and I think once she's able to, there will be ample room for her, not to mention when she gets to a booster.
I don't think you could put a rear facing anything behind the drivers seat and be comfortable, I'm 6" and can't. I also think you'll be really crammed with more than 1 kid back there.
Here's a picture with her infant seat:
Here's the convertible seat we have now (Maxi-Cosi Pria 70):
*The Pria 70 was the smallest front to back convertible seat we could find when in the rear facing position.
TLDR; an infant car seat fits in the middle, as they grow you will get more and more room back.