Basically… to make a proposal spend a bunch of time to write it in the best way you can. Consult all your friends for advice. Concentrate on keeping it short but very clear what the intent is. Look carefully for any current Specs or Interpretations that would have to change or be removed. The official language is English, try to get it correct. Send it to your Continental Governing Committee as an Official Proposal.
I think the wording in the EPIC agreement for making proposals is written incorrectly. It does not directly provide a way for class members to make proposals. It says that proposals may be submitted by either CGG or the TC, but does not mention submission be class members. I think if you send a legitimate proposal to the GCC they will move it forward.
Always keep the guidelines from the Constitution in mind when making a proposal:
It is intended that changes in the OFFICIAL SPECIFICATIONS be limited to the following purposes: To make the yacht safer to sail, to minimize differences in sailing performance associated with the design and construction of the yacht, to make it easier or less expensive to build, to make the yacht more durable, and/or to clarify existing specifications.