Car mirror for no headrest/sunshade

Help! My old Altima has headrests in the back that aren't moveable they are fixed like still attached to the seat, so like 99% of the backseat mirrors won't work with them because I can't strap it to it? How the heck do I see my baby then? Also, any ideas on how to block the sun from the back window? Do they make sunshades for that? Is that illegal lol? Today I had to take her on errands and depending on the angle of my car the sun was beating down on her from the back window. Ugh.... Help!