I bought a pair of the femskin silicone hip pads and they are great, but yeah it only adds about 1" to each side. They feel incredible to the touch. Super realistic. I've also made my own pads out of 2" foam using a knife and some scissors, it was pretty easy but it did take a few tries to get the right shape for me.
Leg affects... Yea I wasn't really sold on those either mainly bc of all the layers you need but also they don't move like a good set of hips would.
The fempads can be added together but they are too expensive for me to do that. I actually just met a mold maker though and might start designing my own set of 2" silicone pads. Happy to sell them if they turn out well

I think my hips are actually concave, haha.