the current paper backups already store 512 bits. Thus, if you split your paper backup into 3-of-5 like my example above, in order to recover the secret you'll be typing 3 kB into Armory by hand!
3 kB as in 3 kilobytes? I don't know what you use to encode the bits in a paper wallet but if you use base 64 you'll get 6 bits per byte, so should only have to type 171 characters from each of the backups, or 513 characters in total.