If we make the following comparisons with boats:
Tiny Hull -> Sea Doo
Small Hull -> Speed Boat
Cargo -> Yacht
Medium -> Oil Tanker
Huge -> Container ships.
You wouldn't put the motor of a container ship in a Sea Doo nor would you put a Mack Truck motor inside a motor bike. It does not make sense for the engine components to be one size only. A Tiny ship has less mass and doesn't need a big engine to move fast.
Similarly shield generators don't need to make a field as big to protect a small ship as it does to protect a tiny ship. There is less surface of protection so if it is one size fits all ships, the shield generator should offer more protection to the tiny ships than it does to the huge ships. Similarly the point defense module has less space to monitor for incoming missles because a tiny ship is a smaller target.
For life support. The machinery needed to scrub the air of 2.5 million crew aboard a transport or colony ship would be much more than what is needed to clean the air of a tiny ship with only 2-3 crew members aboard. If you truly want a tiny ship to have an extended range, then by all means use a colony ship life support module on it. Otherwise use a smaller module.
Perhaps ship components space units should be represented as % of total space available or have different size components which take into account the different hull size.