Negotiating equity comp in an overvalued startup

I've worked in startups for years, and have become pretty comfortable negotiating compensation, but I've recently been thrown a curve ball. The startup I'm interviewing for had a massive valuation during their last round, but due to changes in the market, they've since had to pivot. I strongly suspect they've lost 4–8x their value. Luckily they kept their team small, and still have years of runway left. Normally I'd look elsewhere, but they have a great team, and I really enjoy the problem space they're in. How should I negotiate equity in a startup like this? What questions should I be asking? Is it as simple as asking for equity based on what I believe their current true valuation is? Should I insist on only receiving RSUs since any stock options would likely be underwater in subsequent down rounds?