I originally cut mine the way you have & it passed. Of course that was a while ago.
You can see many troopers on-screen that have hacked-up thighs for running scenes or whatever, so it's accurate.
When I built my sandy, I really wanted to keep the details on the rear of the thighs, so I cut about an inch all the way around the top of the thighs. I was careful to measure all the way around so they'd keep that smooth, pointy shape at the top. With some careful shimming, they came out good & I have great movement.