The last pair of trews I altered (chinos though, not jeans), I took in the inseam only for simplicity, and they hang fine even with might lighter fabric than jeans.
If you're feeling brave, you can fix the hip width by taking in the seam down the centre of the seat. Probably not the approved method, but even though it was a bit of a fiddle around the crotch (oo-err mrs), it seems to have worked okay.
These were all single seams, by the way.
bm