I believe the extra Lifesupport is worth more than the extra Skeleton space. The extra lifesupport would mean that we have a guaranteed, invulnerable bit of LS. This is great, given that all our power and mining systems need Life Support.
That said, I can live with the extra Skelly-space.
Anyway, here's some proposed fixes:
Dust Drive Array
One dust drive is easily damaged and hard to throttle, which is why it has been replaced by an array of 5 smaller Fission Dust Drives taking up the same amount of space as the original large Dust drive. Thanks to independent systems, the Dust drive array can continue operating even with severe damage to some of it's parts.
As an added bonus, the use of the emergency shutdown on some of the drives allows the drive to be throttled fast. (Increasing power is still slow though)
Super Prompt critical Operation
Super prompt criticality is a technical name for an extremely rapid, runaway nuclear reaction. A thing normally avoided in the Dust reactor operation, but which is the core of this new operating protocol. By running the reactor is operating mode where the fission reaction is always maximized, we avoid the problem of uncontrolled power increases as there's no way for the power to increase.
We maximize reactivity by introducing moderators, neutron reflectors and decreasing the size of the magnetic field (causing the dust to become denser). This increases power production, which is countered by putting less dust inside the reactor at any one time. The result is a reactor which can not suffer a runaway criticality event, as the reaction already occurs at the maximum rate sustainable by the amount of fuel inside the reactor.
As an interesting side effect, we lose the ability to control the reactor by controlling it's reactivity, but gain the ability to control the reactor by controlling the amount of fuel inside of it. Thanks to the high reactivity, the dust pellets are rapidly used up, allowing us to easily throttle up and down.
I had suggestions for the Flashlight and Whipple shielding, but they've been rendered redundant by the GM or by me reading the description properly.