this is a tough one. i,ve never done this, but read of it in plumbing a house by peter hemp[great book!]
make up a copper manifold ,same diameter as service ,usually 3/4 or 1"
using tees , make up 4 to 6 -18" risers with end caps. copper union at each end, and full port valve at each end. place this assembly inside house after pressure reducing valve. now in time, when they fill with water you can disconnect and dump water . good luck and get the book ,you won,t regret it