As I was growing up working on race cars and hot rods - playing inside the rule books became second nature. If the rules say you must then you must if the rules say you may than you may - if the rules don't say you must then you don't to. We often read in things that aren't really required (like the rule that said "control arms and spindles must be OEM, no cutting or welding." - DID NOT SAY OEM FOR MODEL OF CAR so we - and several other teams - put OEM Caddy arms and spindles on a Nova... those that limited themselves to Nova arms simply did not roll as fast in the corners - and cried cheater) but if ya dont know the rules - you car doesn't pass even if you tried - they don't give points for style and effort.
In other words we KNOW you gotta have amber turn - that's a given. But how much lens surface area? How far from brake light, marker, ground, edge of vehicle etc is allowable? Does it have to be reflective and what color in refraction? A google of tri color eu lights for JK shows some pretty LEDs - but are they EU DoT approved?
Hmmm - in your position I would call a Germany dealer and see how much the taillight assembly they sell for use on their vehicles runs.... and take that cash with you, buy and pass inspection there (or even buy and have shipped if you're confident - which if bought from a German dealer I would be) rather than hunting a solution and fixing it here - only to find out it doesn't pass for some dumb reason. Anything you buy stateside (especially if it DoT approved) may not pass in EU - simply because to get US DoT approval luminosity, color, visibility angle - all are different standards in US than EU!
J Wm Bishop EA, ASADE
The wagon should, of course, be as light as possible, but strength should not be sacrificed to lightness, for on any but the regularly traveled roads, the wagon will get many a hard knock