The thing is, savior resistance is not that useful.
it may be kinda useful now, but as you begin to rank up it will be worth less
Instead, replace the resistence with an epic iron plating
If you replace one of the heat capsules with a epic iron plating, you will have 200 more health.
Once you replace your interceptor with a legendary zarkares, you will have much more health, heat, and energy.
Then you will begin to rank up, and farm better campaign missions, and eventually reach your first myth!