Would not the SS Electro-Plasma skill help offset the drain?
AFAIK they will only accelerate the regeneration of the power, which in the end will help offset the drain. On the other hand, I thought, that the Power Insulators would be able to prevent the drain from happening at all or at least to reduce the drain.
Power Drain from multiple weapons firing simultaneously is currently not intended to be mitigated by any gear or skill setup. The drain is not a gradual reduction of your available power, but instead an instant reduction in your available power. The moment a weapon is done cycling, your energy level pops back up to where it belongs instead of continuing to drain the longer you fire.
This drain is specifically in place to encourage players to try various weapon load-outs, instead of always running into combat with nothing but beams/turrets a-blazing. In other words, more weapons firing simultaneously is not always a good thing in STO, and this is by-design. It is possible, in fact, that firing 8 beams at the same time may do -less- damage than firing 4-6, simply due to available power levels.
If you find your Weapon Power dipping too low in combat, you might try swapping an energy weapon out for a projectile.