You will need an absolute reference, if we assume there is no such thing as perpetual motion. You can't have it boths ways (no perpetual motion plus relative reference and relative mass), unless you wish to perform science magic tricks.

If we limit ourselves to just time and distance, relative reference has utility. But since SR has three equations, you need to be careful since this utility does not extrapolate to relative mass. With mass you need an absolute reference or else mass is not absolute, but is like a ghost that can get fat or skinny based on how we look at it.

The C-reference aether analysis, that I presented above, is not based on relative reference. It is based on an absolute reference, since you can not fully define the aether above, in finite reference, since any locus of finite points (reference) can only express a fraction of the aether C-point. This creates the fraction of a point paradox, which precludes the aether being subject to relative reference.