There's also the Goblin with a Ecotec-based setup: https://dfkitcar.com/specs.php
Honestly, though, I would not put a Locost or an Exocet in the same category as a Miata or MR2 Spyder. I can just hop in a cheap miata and run errands, get groceries, whatever, and I don't really have to think about anything. Driving the Locost is a lot like a motorcycle: There's a checklist before I get in it - What's the weather going to be like? What do I need to carry? Am I feeling alert and on top of my game? Are there any speed bumps or steep driveways or gravel roads on the route? And if we're talking about more than 10 minutes at highway speed, there's the full-face helmet requirement, just so I don't go deaf or blind from the abusive wind buffeting.
Admittedly, you could build one with, like, bushings in the suspension instead of heim joints, and maybe some ground clearance, and that would help a lot. But it's a really limited-use toy even compared to something like a Miata, at least for me in a midwestern state.