Fuel transfer seems like a trivial problem next to the reusable heat shield. And even if for some weird reason it never works, the program could likely pay for itself just launching Starlink/Starshield with full reuse.
I don't know -- that fuel transfer scene in Armageddon was pretty sketchy!
Or use SuperHeavy to launch non-reusable second stage and fueled Moon module of different design. After all SuperHeavy doesn’t have to be used exclusively for Starship.