I've tried the half-a-long-string trick for a small instrument (actually baritone (20 inch scale length) ukulele strings on a sopranino uke (11 inch scale length)). They sort of worked, in various tunings (from GCEA to DGBE) and I could get two sets from one - but - they were really a bit too thick for their length and the sound did not ring out as well as wth thinner strings.
I believe there is a rule of thumb to do with the physics of string vibration that says that a string needs to be at least 200 times longer than its diameter - otherwise it vibrates more like a bar than a string.
Before you buy strange strings to chop down, I would suggest getting a large piece of paper and drawing, fairly accurately and to scale the nut, frets and bridge point (i.e. scale length) of your instrument and also of whatever the strings are designed for, with all the bridge points lined up - then you can easily work out which fret corresponds to which note on the different strings at their correct design tension. Use this knowledge to select appropriate strings. Strings far below their design tension are floppy and tend to sound crap. Strings far above their design tension may sound bright, may break or may rip the bridge off your sound board! There is a fair bit of leeway in tuning, but the amount you can vary the tuning of a string is not infinite and in the case of thin, high strings like a guitar steel top E it does not take very much tuning up above normal to break them.