Old-school Martha Stewart is not where we are. You’re overthinking and over complicating this. If you search Pinterest or Instagram, you’ll find that clean, simple displays are very popular. People use scrapbook paper, wood/faux wood for backdrops, etc. If you were making hope chests or something large, you’d want a big scene. For what you’re making, you just need good lighting and maybe a small prop or two. And many people use digital mockups for product displays.
3 pieces of foamcore isn’t going to do it, but you don’t need to redecorate either. Take your inspiration from social media… it’s driving the aesthetic right now.