What's funny is that @SnakThree is right, but is proposing a pocketknife where a machete is required, yet will tragically never be able to be used.
The problem isn't scanner range.
It's the player list and/or third-party communication software.
As a guy who likes a bit of the pirating, few things vex me further than any piracy interactions I may have outright drying up before they can happen because the traders I know to be traders when I mash Y because I've robbed/killed them in the past recognize my ship name as a pirate that has robbed/killed them in the past when they see that New Player in red text.
And sometimes, one is on a chat, and they see their ship's name come up and a dude saying "This guy is a pirate, let's log navy and kill him".
Peeps get way too attached to their pixels here.
tl;dr the player list is too good of an early warning system, scanner-dampening fields wouldn't really change much.