Welcome to the forum, Mandylew.
I have made a kilt out of a duvet cover folded doble, as the lower edge of a kilt is traditionally not hemmed but uses a fairly heavy fabric with a selvedge, The doubled duvet fabric gives both weight and that closed edge.

Presumably, with your recycled suiting there will be no selvedge. Maybe you could bind the lower edge with a soft tape or ribbon rather than do a folded hem, or overlock the edge and leave it at that. Box pleated kilts are usually very smart and exquisitely fitted and tailored - probably the best choice for a kilt made from reused fabric though as they are usually a less yardage option.

I hope your project goes well. Do let us see how it goes.

Anne the Pleater