I don't like the ether idea because space is clearly a vacuum. My idea is almost existential: in the case of relativity, perception is reality. Because we use photons, or electromagnetic fields, to measure everything around us, then we automatically experience relativity as reality. It doesn't matter if the universe is submerged in some kind of ether, because as soon as we can measure lightspeed as a constant, the algebraic consequences of that observation apply to us as well. Time dilation, space contraction, mass increase, we feel the effects directly, no matter how abstract or spooky.