I am Not a tech, but I do have a 2007 Subaru Forester (I think the 2005 and 2007 are quite similar) and was hoping sharing my experience struggling to fit a rear facing car seat outboard might be of some help. We have a large Britax convertible rear facing at less then 45 degrees (for toddler) behind the front passenger seat. It is a tight fit. At 5'5", I can fit in the passenger seat in front of it, but at 6'4", my husband is crammed in. But the Britax seats are big and there may be a better choice, especially if you don't need a taller capacity seat like we do (our girls are really tall). It depends a lot on the height of the adults needing to fit in the front seat too. If you were able to fit a rear facing infant seat behind your driver, then you are probably not that tall and can probably fit a convertible rear facing there too.
FYI: We also tried a smaller 2007 Graco Comfortsport, but didn't find it to help much with the space issue and it installed too upright according to a tech, but we did not bother trying noodles, etc. so I cannot say if we had been determined whether we could have made it work and other Comfortsports might be different.
I hope this is of some help. Just be glad that isn't your main family car.
good luck!