new idea: The Vespene that is needed as a fuel for transport mission and deploy mission should be  different.
Since the transport mission has a return trip but deploy mission is only 1 way trip, it is not logical to spend same amount of fuel (Vespene) for both missions. "The Deploy" mission has to require 50 %less vespene than the "Transport mission"

The second half of fuel used on deploy missions is delivered to the object it is sent to (if owned by yourself) or spend on the return journey if the deployment is not possible.