Hmm, how about a compromise then:
- not infinite, but up to, say, 20 rockets per silo (maybe make in configurable up to 50?)
- generate a prototype for each level
- when researching next tier, unlock crafting of next tier silo, and lock previous (probably via callback, not sure if technologies can "lock" recipes natively)
- if there's a callback for completed research, either replace all silos with a script with a new silo with increased capacity (but then you'll have to also copy all the silo's settings) or notify the user to (?quick-)replace the silo manually