I would suggest you try and install the seat more upright. What convertible do you have that you are trying to install? The 45 degree angle is for babies, but since your daughter is older, she can have her seat installed as upright as 35 degrees. That will give you alot more room to install the seat. Also if you can fit an infant seat in the car, you can get a convertible in as they don't take up as much room since you can install them more upright.
If I can fit a rear facing Britax Marathon in the back seat of a chevy Aveo subcompact without having to adjust the front seat at all, I'm sure you can get your convertible into the back seat!
You can have the car seat touching the front seat, as long as its not braced (pushed up against tight) the front seat.
Also you can find a tech at www.safekids.org, a CPST to help you install hte seat properly.
Good for you for keeping her rear facing as long as possible! This is a great decision, doing everything you can to keep her as safe as possible!
EDITED TO ADD that while I know the original poster knows Gamma G's answer is wrong, many may not. A rear facing car seat is outgrown when there is less than one inch of hard shell above the childs head, or the child goes over the rear facing weight limit. Feet touching the seat is NOT a problem and no reason to turn a child around as there has never been a documented case of broken legs in a rear facing child. On the contrary, one of the more common forward facing injuries is broken legs.
A rear facing child is 500 times safer in the car than a forward facing child, as in a crash the seat keeps the childs body aligned, the head and neck supported, and the body is cradled into the car seat instead of thrown violently forward.
Rear facing is recommended by every car seat manufacturer, NHTSA, and the AAp recommends children remain rear facing until they reach the limits of their rear facing convertible car seat, or at least 2yrs and 30lbs.