I'd long been aware there probably won't be enough of the main colour to do the pattern as shown.
So I'd been hopping around a bit: the back up to the top stripes, then each of the fronts to the top stripes. Above the stripes, I'd planned to continue with the very pale colour to the shoulders.
On my second front, with two rows to go to the start of the stripe pattern, I had this much main colour left:

And then I looked lower down, matching the stripes earlier in the pattern:

And I looked higher up:

There was a definite difference in length! Only two rows, but when each row is about 0.6 cm, two rows difference is a lot.
So I frogged - lots - and knitted it again, and forgot to take any photos. I just had enough of the main colour to finish that side, with about 30cm to spare. All is well with the world.