The locust must have Endo Steel and Ferro at all times.
This isn't too hard as it only costs 360,000C-Bills to get both and max armour.
This is your new armour layout:
LCT-1E
It will terrify you, and rightly so.
But you simply don't have enough armour / internal health for it to really matter.
You're 2/3/2 rear armour is enough to take an AC10 hit, and to deal with laser passes.
You cannot put enough armour there to take anything else, without making both the front and back incapable of taking a hit.
You're using that impressive torso twist to use your front armour as rear armour when running away, and your speed everywhere else.
By splitting it this way, you can comfortably take 1-2 shots of AC20 to the chest and survive.
When you're used to this or feeling more daring, it'll be time to move to this:
LCT-1E
The 5/1/5 on the arms and head honestly won't make much difference once you've learnt to pilot.
This works because your cockpit hitbox is almost nonexistant.
In some 400 drops in a Locust, I've been headshotted maybe twice.
There are those that run
no head armour and just rely on the base 15HP.
I like at least 1. (That red/yellow arrow bothers me in the mechbay.)
The 5 on each arm is workable because they have pretty tiny hitboxes, especially from the front (you rarely get shot in the side / arms), and with 12 armour on each, I rarely if ever lost an arm.
Witth 5, I'll lose an arm on occasion, but it's still pretty rare for me to lose an arm before I simply die.
This layout also gives you 7 tons for weapons with the XL190.
Additionally, to allow you ton understand engines a bit better, a chart detailing the total weights of engines + heatsinks can be found here:
For the ones greyed out - there's no point in even owning them.
Engines with more power, and/or more internal heatsinks exist for the same weight.