[Suicide Junkie]

The fighter/carrier fix suggested below is a good idea. As for bases, IMO, they should not have unlimited supplies, but rather be given a built-in supply storage and solar generation ability of 5000/500 or so.

This could be done now, and would only mess up the player stats and AI designs.

Just:
1) Change the vehicle type of "bases" to "ships"
2) (optional) add built-in supply storage
3) Tweak all AIs to use ship hulls versus base hulls properly. This may require adjusting the size of the bases so they are different from any ship hull, and could be a lot of AI design_creation work.
4) Suggest to players that they include extra supply bays and solar panels on all defense bases.

For Humans-only games, this could be modded in 5 minutes.
For humans only, another trick you could use is to remove resupply facilities and quantum reactors, forcing the construction of SolarPowerStations, and essentially adding another resource to the game.