If heat travelled better, then a lightweight heat resistant suit would be useful. Nothing fireproof, but would protect you from extreme heat better than nothing, though worse than a real firesuit.
Also, have a single engine maintainence armor set that is immune to temperature extremes entirely, is basically power armour made of an inch of solid steel, and has a battery that is depleted when it is actively protecting it's occupant from heat or moving. It sould be possible to move in unpowered, though incredibly slowly, and even unpowered should hold off high (or low) temperatures for a few minutes even without power. It should be immune to all forms of damage, but travel very slowly(1 tile per second powered, 10 seconds per tile unpowered) and have it's own air system from a tank holder that can only be accessed when unoccupied. It should be worn by stepping onto it. A user should not be able to carry aything, have a suit on, wear a mask, or have anything on their back, and must be free to use both hands, to utilize it, as it replaces internals and mask and has it's own back slot. Exiting should cause it to drop anything it was carrying. To exit, the user should click on it's icon, that should appear in the suit slot. A user unable to wear it should be unable to walk over it. Zombies and monkies should be unable to use it, or better, a /mob has a /var to indicate if they may use it, and certain diseases and races disable it by default. That way, an admin can override the ability/inability to use it. Or maybe 1=yes, 0=no, -1=default, and it is -1 unless set by admin efforts.
It should be unable to use certain objects that require fine manipulation, including firing guns, using injectors, and manipulating tools.
It should only restore energy at docking stations, and in the engine area when sight of an active remote charging node, initially only lining the engine. What else... Maybe the use of a multitool may access advanced settings such as the ability to lock it so that nobody gets in or out, and the ability to disable sets of limbs, allowing for it's use as a portable prison for desperate captains, and a traitor with a cloaker and a multitool can use it to "capture" an engineer. It should block radio signals, but have a built-in(disableable) headset. IT should block all sound unless it's audio systems are on. It should have built-in meson scanning mode that drains power, and is also disableable.
If it takes damage to a system, you must disable the system and then apply the right type of component to fix it.
Maybe it should have the damage immunity of IT, but be limited in the damage it can do because it is too bulky. Maybe it can be rewired to overdrive the motors and become hulk-strong, but with each action have a chance to blow a random system that must be repaired.
It could possibly have a set of powertools built in.