My thought was that invisible + fully shielded could be an OP ramming ship. I guess as long as either weapons (as you suggested) or shields are limited by cloaks, it shouldn't be too imbalanced.Could you think of a reason why cloaking would necessarily interfere with shields? From a visibility standpoint, shields don't light up unless you're hit, which would drop your cloak anyway, so having shields on doesn't seem as though it should give away your position.
Also, @CMDR Cosmic Spacehead suggested that having night vision on should reveal artifacts (or possibly a blur) that indicate the presence of a cloaked ship, making it thereby partially visible or detectable to the trained eye, and more so the closer it is. I think that would work better than having the cloaked ship partially visible all the time, as in a way that would somewhat defeat the purpose of cloaking to begin with, particularly considering that the cloaked ship still shows up on radar.
The Metamaterial Armour I suggested could be made significantly heavier as you suggested, and I think that would also be a good trade-off, but perhaps not to the point of severely limiting manoeuvrability, though it should take a noticeable hit due to the weight increase.
The reason I suggested that deploying weapons should deactivate the cloak is so that there's a slight delay between decloaking and firing on a ship, revealing the cloaked ship just before the first shot can be fired.
I think though that a large power draw for the cloaking module would be a good way to restrict overpowered stealth fighter builds that would otherwise have had a stack of Shield Boosters and Shield Cell Banks, so that would be a good way to limit shielding on these ships without actually having the cloaking interfere with the shields directly.
I will incorporate some of this feedback into the OP. Thanks.