You don't have to use just one "fixed paragraph width."

Set it, per user, dynamically. Browser detection provides you a basis to infer a maximum char_count that should be useable on the narrowest_likely screen. And in some cases, ENV detection can give you the info to set your max_line_length more precisely. Alternately, have user supply a desired width as a CL argument. ('course then, you'd better check their input for safety too.)

Either or both are "doable," but add complicatations.
Duh! I'd forgotten the answer is in the original, so out of curiosity: why do you want to preserve multi-spaces?

If it's solely for readability that's one thing; if you need the info, is there some good reason not to

t/\s{2}/~/;
t/\r/(something else)/;
[download]

to catch whatever you really need?

Questions are likely to be IGNORANCE_based