If Lute has enough MAG a 1 turn of Chp 16 is possible if you have a 2nd Warper.
And both uses of Hammerene go to warp. You only need to use Rescue 2 times.
My warp uses always go like this:
3 Warps on Chp 16
1 Warp on Chp 17, repair it.
4 Warps on Chp 18, repair it.
1 Warp on Chp 19
2 Warps on Chp 20
1 Warp on Final part 1
1 Warp on Final part 2, it breaks.
You will need to use rescue on Chp 20 and on Final part 1.