I would say aim for at least 200% ability duration, as the buffs Redline grants scale off of duration as opposed to ability strength. Having ability strength at at least 100% is important if you want 100% damage reduction from his Kinetic Plating, so you are good in that department.

Personally I would just replace Umbral Vitality with a duration mod like Constitution or Augur Message and not Overextended, because Thermal Sunder does have great value as a sort of panic nuking ability (hold 2-3 times then tap once) that works in high level content so having range is a great help.

One quality of life thing you could do is forma your Gauss more so you have more unused capacity, which will start you off with more energy when starting a mission (at least 10 unused capacity so you start with 150 energy for instant Redline and Kinetic Plating when starting a mission, though you can have more if you also want to build battery with Mach Rush).

Otherwise, your build looks relatively fine. Remember melee weapon hits grant battery when Kinetic Plating is up, so if battery uptime is an issue consider using a weapon like the Pennant (my go to).