We have an outback as well, and I can fit a Maxirider, a convertible safe n sound and a cheap target booster in the back. The are literally jammed in but as long as the bases are sitting correctly is is okay, try towells underneath if you need to raise parts of the chair.

The pain in the bum bit is getting to the buckles, we attached long straps to the buckles so we could easily find and pull on them them, still you have to get your hands in the actually clip them up.