FL/PE3 question

I'm currently working on this element (today was my 3rd session). I found it to work my hips a lot harder than my core, that it's barely challenged. My straddle isn't that good at all (it's around 90 degrees), but when I perform this movement I try to keep my legs as spread apart as possible. Should I keep my legs a little bit more close to each other to challenge the core a little bit more or should I continue to work like this, getting stronger in the hip area (that is not really strong in my case)?

I benefited from working the hips in this PE. Match the straddle in the course material, if that works your hips then that's fine.