well, you weren't incorrect in where it was from (aside that it was also part German), but you said it was built by a well known car/boat designer. it wasn't.
Opac group is a prototyping/fabricating company, NOT a designer at all. that's where you had your wires crossed.
the Swiss company, Status & Class were the designers, Opac were the builders, and it was Mercedes G class based.
even if you had given us either of the company names, you'd have still not been able to find it easily.
so this is why i find it hard to believe you really did try you're hardest to triple check.