While going out to the edge of a system to where the "gravity distortion" is low is simple enough with a single-star system, it could get interesting with multi-star systems. How do we handle the case where a pair of not-terribly close-together stars of similar mass (say two stars roughly equal to sol, but with an orbital separation roughly equal to the orbit of Jupiter) where as time passes the acceleration and potential energy at any particular point changes.
For a story you don't worry too much about that sort of thing - you can write your special case, like the variable Alderson Point in The Gripping Hand. But for a game you have to manage the general case; not get bogged down in calculation or create "laws-of-nature" that are going to call for interstellar routes to change with time.
So, potential energy and momentum still non-negotiable; what sort of system might work? Or do we have to relax our chosen constraints a bit; or wave our hands a bit faster with binary stars?