Would be pretty easy, if you didn't get too carried away! (Don't know what your sewing skills are like!) Buckles and straps would be easy enough, just sew 'em on, zips, I guess just cut a slit in the fabric and turn the edges, stitch to zip?
Also, have a look at
www.gothichaven.com, they specialise in "plus" sizes (what a yukky term I think) for the...wait for it....Voluptuous Vamp. Think that's you! Didn't see any bondage trousers, but they could poss advise where you might get some.
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