Our parents separated when my brother and I were young (5 and 3), money became much tighter as we were two households on one household income. I watched my mother cheerily (likely for our benefit and also just to cope) try to manage on a very tight budget and go without things for herself. We had a lot of love so were happy, we were aware of money being tight but not worried about it.
We did however become protective of both parents and worried for them. I was worried my Dad was lonely without everyone in the house and I was worried that my Mum didn't have things for herself. This worry was amplified by the fact that they were both single parents, I worried for them both being sad.
I would have been really upset to see my Mum sleep on the sofa or in the living room not even having her own bedroom. We already saw her have to not have and lose enough.
My brother and I shared until a year or so before the separation, then had our own rooms (I missed him!), then again for a while when there was some decorating/work going on in his room. I don't remember how long we shared for but I know it was quite a while and I liked it. Pre-puberty it doesn't matter if kids are girls or boys, they're kids together. Plus these kids are going to need each other. My brother was the only one who knew what we went through and we were in it together, that shared experience that shaped who we became as young adults and to this day has kept up close. We both are doing well now and turned out well, but we were both profoundly affected, no doubt. The challenge is to have that effect not be damage.
I'd be much more upset by seeing my Mum not have even her own bedroom or sleeping on the sofa than sharing a bedroom. I liked sharing, we were kids and good for each other. Once a parent seems alone, even if they don't feel alone, a child will worry for them.
My advice, from the child experience point of view, is have your own room (with backup space for the littlest one for sleeping times if needed), to show your kids that you are not suddenly second class, or suffering, or losing things. They also need to see that independence from a relationship is not necessarily a bad thing, that you have your power and are not being diminished or reduced. To me that means having your own room, your adult space, where they know you are coping and life is ok for you. They value you and need to see the world value you too.