I think the sound comes as much from the way the cadences and accidentals fall to hand - the same reasons why alternate tunings give a different sound to the guitar. For that reason, when playing for the morris, I largely use a short-scale bass guitar with custom strings tuned upwards GDAE from what is usually the bottom G on a bass guitar.

If you are going to tune a mandolin to the same intervals (and pitch but an octave up) as the top four strings on a guitar (DBGE) you are going to need custom strings as otherwise the lower three courses will be MUCH too tight.

You won't get the sound of mandolin chords, though. The inversions will be different.