One of the may arguments in support of paying for the privilege of Hugo voting is that the awards are given by the WSFS, and you have to be a member of the organization to vote. However, this gets missed by a lot of newer fanish types who don't understand that membership in the Worldcon is membership in the WSFS for the same year.
So my proposal, which would require amending the WSFS constitution, would result in renaming a Worldcon supporting membership, but would probably also do some additional background adjustments.
Specifically, I am thinking that the WSFS should charge a membership fee, which can be paid two years in advance. Since the WSFS doesn't maintain its own finances, they would as a rule pass the process or collecting the fee and maintaining the membership of the organization to the seated Worldcon for the year the membership is good for. Further, they will provide the seated Worldcon funds equaling the membership fee for each member for the purpose of administering these funds and lists.
Therefore, in order to nominate for the Hugos, you must be a member of the WSFS either for that year, or the previous; and to vote you must be a member of the WSFS for that year. Similarly, in order to vote in site selection, you must be a member of the WSFS both the year that the voting takes place, and have agreed, and paid in advance, to be a member for the year that the site is being selected for.
As proposed, this makes no real change in how we work. It just changes the name from "Supporting Membership" to "WSFS Membership."
Of course, at the same time, the WSFS could set a fixed amount for this, and allow the for a higher supporting membership to the convention that would include convention publications -- with WSFS members who are not convention members only getting the ballots. But that is a somewhat separate addition. In order to make this addition work, there would have to be serious discussion about the need for an additional voting fee on top of the future WSFS membership dues to vote in site selection.