Weapon core stored at site A, electronics package at site B. Wow, that was a tough one to solve.
You are forgetting that these are designed as infiltration devices, not "flight line" ready.
The electronics includes all the wiring for the bomb. Unless the bomber knows how to wire nukes, that won't hold (and why would you send someone that educated to be a martyr anyway? you'd only get to use these things once, instead of having him churning out more bombs for you). These were infiltration devices, yes, but designed to be supported by a massive infrastructure, that could bring them in and out when needed for maintenance. They aren't "fire-and-forget" simple.