Just get a disposable one and set it on a sturdy cookie sheet unless you have tons of storage for rarely used cookware.
I love the buttermilk brine by Samin Nosrat.
https://cooking.nytimes.com/recipes/1021523-buttermilk-brined-roast-turkey?smid=ck-recipe-iOS-share
She spatchcocks in the recipe which I haven’t tried before but sounds like a good idea.
Three sides are enough IMO. Have some bread and maybe a salad, too.