Please first of all, check once more if there is really no suitable alignment available in the configurator. The following approach should only be necessary in exceptional cases:

The key point is “head-to-head”. If the head of the design is seen on the first page on the right, it must be seen on its back page on the left. If front and back pages are shown side by side in the chosen alignment, they are positioned head-to-head and will be correctly printed.