You'll have to use 2 or more shield groups to cover your entire ship. Their balance is made that eventually, with a big enough ship, shields will need to be spread out over multiple groups to have full coverage.
This makes parts of the ship less protected but for a ship that size, you should have no problem providing decent protection against ships that are smaller than yours.
With the weapons update, we're going to tweak shields even more as then the improved armor scaling will also play a part, not to mention that each weapon will be different to what they are now. I've had feedback already that mentioned shields were too weak, or that its power consumption is too much.
From what I can see, it's mostly the shield upkeep and the fact that shields recharging is a all-or-nothing mechanic right now so I'll be looking into changing those numbers up when needed. We could bring back the shield regen under fire too if it's simply doesn't want to cooperate with the weapon and armor changes.
That said, most likely the shield radius will only change slightly and I have no doubts that you'll need more than 1 shield group to provide full coverage. As you said, your current shield covers a lot of unused space so most likely you won't even need a strong shield group to protect that specific unused area as it simply doesn't impact your ship performance if damaged. A small shield to just protect against smaller ships would be just fine in such a situation.
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