The pances are finished. Basic black nylon trousers, extra puffy in the bellydancer (lol) style. Basically he needs "lunging" room, and he's going to tuck them into his boots, so the puffier the better. I can provide a pattern for them if you like. They are ridiculously simple.
LAIL!!!!!
As someone who has studied The Arte of Defence and tried it in both slops (puffy pants) and hose... there is no such thing as "lunging" in baggy pants... at least not in any sane sense. Of course, there was no such thing as "lunging" in rapier until the 1700's. Mostly people trying to kill other people, did not commit insane movements such as lunging, since missing with the point basically leaves you entirely open to being dead, before you can recover.
Di Grassi came somewhat close with his long step, but even that was only of a "pace or two". Crazy Lunging came about as a part of sport fencing in France.
There does exist some evidence that at least one French school taught a lunge. There's also evidence that this didn't work well, since the Spanish and Italians simply parried such that the Frenchmen impaled their eye on the quillion.