Massive number of ships??

[tesco samoa]

that would help

or just make homeworld centres that produce 10,000 of each resource,

value improvement for the planet by 3%
storage of 100,000 for each resource
resource converter that converts with 20% loss
reserch ability and intel ability

and to top it off.... have them act as a space port and a resupply port

and have some cargo space as well

Still it will take a long time to build 20 k ships

most i have had is 3000 in a game

with about 30000 units
and that was expensive

also you can decrease the maintence to 1% or something