How to get the effect of gluten in gluten free baking
According to this site I've been using (https://www.americastestkitchen.com/guides/gluten-free/troubleshooting-gluten-free-baked-goods), if your cake is too dense, try: "Reduce amount of fat, use additional liquid, use additional baking powder, use additional egg." So I would try each one of those things separately and see what gets the result you want. I've just started experimenting with gluten-free baking, hope this helps!