I did search for monocoque chassis as well, but they are also not allowed in Denmark. The rules are VERY stricht. They could be approved, but they would have to be produced at a factury and they needed to go through the safety procedures as well. So it is impossible for private people to build anything like that. IF I wanted to go through that, it would cust me around 200.000$ to get those qualifications. That is insane
The only reason why it is possible to build it on a VW Bug pan, is because VW back in the 60s actually went through all the steps. They paid for all the tests and safety procedures. After that, they gave the approved papers to everybody for free. That is the reason why it can only be a VW Bug that I use. I just need to print out the papers, and bring them along when I get my Cobra MOT.
Btw, both your cars look awesome. Totally cool all the way.