I used hair canvas on my PV St Davids. I didn't cut the pleats out because it is a 5 plus yarder and the thinner PV didn't have much bulk with one inch pleats. I guess I didn't need the canvas but I did it anyway. I'll just dip it in the tub with some woolite when it needs it and hang it to dry. I did consider only using the hair canvas on the aprons but decided that it needs to be anchored to something of substance on the pleats.

I would recommend it. My Clark 8 yard mostly handsewn kilt has hair canvas and a my Hunting Stewart 5 yard does not. I've noticed I can strap my PV kilts with interfacing a little snugger without distorting the tartan or getting that fold in the aprons.