It's more the other way around. The 4D model is actually a better representation of the "real world" object, and it is the projection of that object onto our 3D perception of the universe that results in our measuring length contraction. Our three 3D world is just a "shadow play" of the 4D reality. We can only directly measure the shadows cast, and must infer the 4D model from that.Very nice explanations.
So, considering all that you have said, if there's no physical change of the object's properties/length in the real world, this means that Length Contraction represents object properties translated from the 3D model into the 4 dimensional space-time coordinates system, where you indeed will have different measurements.
With the red arrows being the detectors and the green line the object with the switches at the ends, then if the switches of the object are detected simultaneously in rest frame of the desert, then the top image shows the length measurement you get for the object in the desert frame. (object shown moving left to right) This will be the length contracted length of the object.In this case, having an array of detectors in the Atacama desert at a distance of 1 mm away from one-another, and an object passes over the detectors with 0.9c (the object has a switch at the end and one at front) activating with both of the switches, simultaneously (in the array frame of reference) two detectors, the distance between those two detectors will be the proper length of the object. Though, if translated in the 4D space-time model, this will measure a Length Contraction.
So you never lose Length Contraction, you don't lose SR, you just have to translate the experiment in the mathematical form of a space-time model to have different readings, which makes sense in my mind. I mean, it was never meant to convince that length changes at relativistic speeds rather it is a different reading in a 4D space.
However, in the rest frame of the object, it is the detectors that are moving (right to left) and are length contracted while the object is its proper length. Thus you get the two bottom images with the object triggering one detector and then the other.
So, you will directly measure the contracted length, and if you know the relative speed you can use this to work out what the proper length is.
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