how about this for point assigning
assign points for singles and doubles the same way ecrc does (look at their page for the exact numbers)
this assigns points to top 32 in singles, and each player for top 16 in teams
then for the final event, the top 32 singles ranked players are allowed entry into the event. if someone is missing from the top 32, we simply add a bye which will be given to the top player, and so on if a 2+ byes are needed. if we need to break a tie, we can either use the people are in attendance (or if theres more, perhaps have them do a quick round robin to break the tie?). players below 32nd spot though can not be subbed in if people are absent.
for doubles, how about this:
out of the people in attendance, we start at #1 and ask them who they want to team with. then we move down to the next person (so say #1 teams with #2, next person open is #3), ask them to find a teammate and so on. keep going till we have 16 teams. obviously the player finding a teammate cant pick anyone they want, lol they have to agree. only requirement for a teammate though to make it fair, they have to choose someone that they have teamed with at an earlier circuit event. the other requirement is that everyone in this final teams bracket has to have attended atleast one anmc doubles event. this shouldnt be a problem however since the same tourney as the final event will also be a anmc event (like a 2 day tourney where first day is the regular anmc singles and doubles, and day 2 is the finals)