What would you replace the claim system with? The previous system whereby you could claim large sections of space with one outpost? How is that better than what we have now whereby you can jump your outposts over an inconveniently placed enemy outpost (provided you can get there by an alternate route of course)?
? The claim system is fine as it is now. Cost is based on distance from nearer owned star. You don't need to dig tunnels in space to make it work.
Distance definition has been changed from straightforward euclidean distance to arbitrary and unintuitive "hops" (in fact now you really have to stop the game and process the map to understand what is actually near and what is not since "traditional map rules" do not apply anymore). But even ft is not related to the visual representation of the map anymore but it remains a number thus it can be used in all mechanics that treat distance as a number.