I like your site, by the way . . .
The Philabeg/small kilt was developed in the late 1600s and has a decent amount of documentation of its use before the 1715 Jacobite rebellion. (It is different than the modern tailored kilt, however)
For the interested, a belted plaid is what is shown in most of "Rob Roy" and what is so messed up in Braveheart (ie-> NOT accurate in time or construction).
A wool loom of tyhe time made a strip 25-27 inches wide. For a belted plaid (great kilt), it was simply 2 lengths (usually 3.5-6 yards, usually close to 4 each) of wool sewn together lengthwise to make a "double width" 54 (or so) inch wide piece.
A philabeg was a single stretch (4 yard) NOT attatched to another. It was probably attached with a belt through loops of some sort (the recontructions tend to fall apart without beltloops or some sort of sewing). I tend to call it a kilt for ease, though it is not a modern kilt. I don't like the term philabeg much (for reasons I'll avoid detailing right now).
I've discussed this (kilted pirates) AT LENGTH with many, many Scottish fanatics (like me) and had VERY different opinions. With the knowledge here, I figured someone may know of some from the pirate side (different base of experience and interest).
Likely candidates: Gow, MacNeils (infamous seafaring clan on the outer western isles), and others from the western isles.
Thanks Foxe!