Any Known Support for Double Precision Coordinates?

Hello,

I'm new to Unity and I'm looking for a 3D engine that can handle a large multiplayer world (>100x100km magnitudes down to mm precision across the whole map). I will have trouble using fp32 coordinates and transformations (as well as height maps scaled up) so I'm curious if there's any fork or official development going on for supporting double precision coordinates. Due to being multiplayer, tricks like scaling down or origin re-basing will not help to overcome the 7-digits limit of fp32.

I also wonder if there are ways to solve view distances from higher viewpoints and e.g. tiled worlds vs far clipping etc.

I understand how complicated this task is so I would not re-invent the wheel. So if anyone knows about any available asset or fork (or planned fp64 support in the near future) that would help me out here, it would be much appreciated.

I know Unity might not be the perfect match, but 3D engines that can handle this (let's not mention names, we know exactly one which is advertised as such :D), would cost five-digits worth of bucks, something out of my reach for just a proof of concept project. However, I can trade in some money, if the solution already exists.

Thank you very much in advance for any suggestions!

Cheers