Faxing might be ok, but for real proof you probably have to do service by mail following Rule 5 in Washington’s Civil Rules for Courts of Limited Jurisdiction. That involves including with the request an affidavit of mailing. To do that you can modify sample text in the rule, and then use the discovery template format while replacing the title and body to suit your affidavit.
If you want help reviewing discovery, upload digital photos or scans (with your personal id and citation number redacted) to any free image hosting site and link them here in your thread. It’s always possible you could have other defense motions based on what you receive through discovery.
Preliminary motions are verbal in most Washington traffic courts, and a deferred finding request is also preliminary. If a prosecutor is present you might be able to come a little early and ask him/her to amend to a non-moving violation.

