I like the idea in general, as for the stealth, I think a stealth "bubble" is the way to go, but the hull idea could be used as a booster, with the hull AND the bubble, a ship should be able to attain almost perfect "stealth", furthermore i agree with the idea (sorry already forgot who posted it) that the stealth should get a bonus depending on the ships state... like if it's moving... firing... they should degrade the stealth effect. of course, "coasting/drifting" should not be as harsh as increasing/maintaining speed...
basically either system would be capable of achieving 80-90% invisibility (this would make a ship a very faint shimmer outline at about 1200m...
the bubble would be adjustible in size, allowing to cloak multiple vessels, at the cost of serious power draw, and the hull would have less armor then normal, it would basically stealth any block "behind" it from the enemies point of view... so if you lose a block, you've lost a part of your cloak too... of course since it's a "layer", it'd use less power also.
the two systems together however, would have an almost perfect cloak of 99%, basically you'd park nose to nose with the enemy ship, and they'd see a shimmer... since the bubble and the stealth hull both use considerible power, you'd need extreme power generation, or a second ships' field... to achieve such a feat... basically by the time you have the power to sustain both systems, your ship is either so massive it needs the cloak to lay a shot before they run, or you've got nearly no defence or offensive ability anyway... balancing this new system out for servers...
of course, the stealth "hull" would be heavy load on a server, since it has to calculate each block that is "visible", to side step that, the "stealth hull" data should be saved to memory, and only updated on events, like if a ship is about to enter "vision" range on a client, the server should check the integrity, and not even send the ship data until it would be "visible" to that client (haha cheaters) (visible means you'd stand a REASONIBLE chance of actually seeing it with the naked eye, even if it is just a shimmer), having this data availible means the server can send the relevant data only, and reduce lag on lesser computers (although INCREASING it on the server side)
I do note however that this would be a hell of a lot of programming, on the flip side, it'd be a hell of a good feature.