Maybe something based on normal cloaking device, but it wouldn't make your ship invisible? The cloaking device is hiding your ship completely (with the exception for sound & some bugs). Maybe the devs would be able to do something with it? Sadly I'm almost completely green with modding FL, I've only had some fun with system editor + a few small programs and I'm not even sure if it would be possible to code something like this. Anyway it would be pretty cool to get it
I've kinda been wishing they had a 'power down' mode instead, and for a long time. Sorta like engine kill, but a power kill. You lose shields, weapons, scanner, lights... but after a few seconds, if you DON't move, you drop off scanner. If you power up you go back to normal. This would allow people to 'stalk' without cloaks, but still limit you. You wouldn't exactly be able to sneak up on someone like when cloaked, but they could come to you. Not to mention the evasion possibilities!
As to whether your scanner should work when powered down...maybe is fair that you also only get eyes only. With this hiding behind an asteroid or even a moon (sit in a 'low orbit') powered down and waiting at your own risk becomes possible). I think this would be cool since you could still see a ship on the chat list. So you'd know there are ships around, but thats all. In the end, maybe a scout would be the best choice as a deterrent. Someone using their eyes, and yes in some places it might be pretty hard! Which means the games are afoot! This would also allow ships to infiltrate bases and other features. Meaning, people might actually have to go searching bases or celestial bodies (when scouring a system) and give them a detailed look. Something most of us don't do anymore, because we know there's nothing there and no point. All we do is chase each other in this game, there's no way to hide and seek on the long term. Yes searches would probably drag on longer than 15 minutes. That would be the point!
Lastly, mines will be mines. They work on cloaked ships, let them work on powered down ships. Maybe make a new mine with longer shockwave range to serve as 'depth charges'. The people in charge seem to have been overly concerned with cutting cloak times, and so there is little long term stealth issues to be dealt with now. But a powered down ship could be a dangerous spy, and if you get the 'feeling' one is around, why not patrol some likely places? Drop some charges while keeping your eyes open! And under this system, you'd have to power up to cloak so don't worry about people trying to double up, or cloak while powered down so they can start moving...If anything this would be just as fun as a cloak in some ways, with a lot of creative things you could do. Also if mines might not work, the cloak disruptor might do well to serve a double purpose, and 'ionize' a powered down ship, no shields, no protection, and would force you to power up being visible again. All you'd need to do is give like a 3-4 sec delay and let it be CD'able and all's fair in love and war. Other than something like this, I don't see new cloaks anytime soon and the ones we have are as good as it gets now.