So: Not only did I get my mattress moved without a hitch last night (folded down the back seats, and everything just fit right in*), I also fixed my typewriter. Slid the carriage all the way to the left, turned it on and off a couple times, and BAM! I was click-clacking away again. Victory dances ensued.
*I've been driving this car for two years and haven't found a name for it, and now Nathan points out the obvious: TARDIS. Fangirl squeeeeeeeee!