When I sewed the shorts with this alteration, the shorts gave me a front and back wedgie. I added a rectangular gusset, which took care of that problem, but made the back look like I was trying to make a split skirt. The front is a little loose, but not too bad.
I had already pieced together small scraps of fabric to make the crotch the correct shape and I didn't have ideas on where to go from here, so I finished the shorts and will wear them for a while to see if that gives me ideas on how to make them more fitted.
I'll compare the first pair and the second pair and see where I need to go from there.