I recently brought a steel string tenor guitar (23" scale), tuned DGBE, like a baritone ukulele, to Gryphon Stringed Instruments, and asked them if they could piece together and install a set of steel strings for tuning DGBE an octave lower than baritone ukulele tuning. They did it, and the tenor guitar actually sounds pretty good. I don't know if I'll keep it this way, but I was glad to see that it was doable.
By the way, I'm one of the (apparently few) people who own a Compass Rose "octave ukulele" (tuned GCEA, an octave lower than tenor ukulele) like the one discussed in the thread for which there is a link in comment #2. I have a steel string baritone ukulele that I am considering restringing so that it's tuned GCEA an octave lower than tenor ukulele, which is a bit lower than ordinary DGBE baritone ukulele tuning, but higher than octave-lower-than baritone DGBE tuning.