The only real way to prevent ballot stuffing is to ensure the users are active and have some reasonable assurances of identity... this is an open discussion. One way to do this is to be a voting member you need to "register" witht he UFoI, which will entail your system admin vouching for you, and you using keyoxide to identify yourself and used to ensure you dont have dupicate accounts.
There are concerns with this approach 1) only technically oriented people who can use PGP can vote 2) people who want to be reasonably anonymous wont be able to vote.
The exact process for voting is one of those things I can think of a doen ways to do each with its own pros and cons and will need to be discussed among the group I think rather than dictated to them.