I went to the Fabric Store and found this fabric, which I've already used to make my vintage dress (about two posts ago). It's such nice fabric (100% cotton, white asterisks on a textured navy background) that I decided to get another 3.5 metres. The plan is to make a sleeveless top from the same stuff, to wear with these super-wide leg but fitted at the waist and hips trousers - for a jumpsuit effect but without the bathroom-related impracticality. I reckon they will also look good with other, short and sleeveless tops.
Having an almost straight up and down figure, I cut a size C from hem to hip, then widened out to size E at the waist. I also added 2 cm to the back and front crotch curve, tapering to the inside seams at the knees. I have needed the latter adjustment in previous trouser patterns and thought I could always take these seams in if I didn't need them here. But it looks and feels fine with these adjustments. I also removed 4cm from the crotch length.
I wanted these to be full length as I'm not sure that a cropped wide leg would look very good on my short stature, so I didn't make any length adjustments. This worked out perfectly.
Also I left out the back darts. Instead, I took the sides in by about 1-1.5 cm at each side from hip to waist.
Its possible I could have just cut a straight size D and needed less taking in at the sides (but have a narrower seam at the waist).
The fit in the end is great. As soon as it's warm enough I'll be wearing these out and about with short tops! And posting a photo of me wearing them!