Justification statement for exceeding the maximum length of manuscript
Assuming it is true, I'd say that I'd made a good faith effort to keep it to the limits, considering whether any of the material was extraneous, but it is still at 37 pages.
But also add that you would welcome advice from reviewers including advice on reducing the length.
I doubt that a detailed technical statement will get the result you want, since the editor may not be able to evaluate what you say since that is more the job of reviewers.
Some papers can also be split into two, of course. Perhaps you have considered that already. Not all, of course, but it is worth a look.