Motorhome magazine publishes an annual dinghy guide and has downloadable PDFs on their website going back at least into the '90s. That's a good way to quickly figure out which makes/models are approved for 4-down towing by the manufacturer.
Make sure to pay attention to the details on those Motorhome dinghy guides. Many models are flat towable, but only with certain options. The early 2000 Nissan Xterras, for example, are only capable of 4-down towing if they're 4wd and have a manual transmission. Just like MG I'd like to find one of those, but the 5-speed option is weirdly rare.
It seems like for small SUVs, jeeps are the most popular on the road. I've also heard that many people like the Geo/Chevy Tracker (aka Suzuki Vitara), but you won't find those unless you're willing to go back 15+ years.
My dream toad is a new Suzuki Jimny, but unfortunately we ran Suzuki out of the American market a decade ago