It's never easy picking just a handful of you with 6 pages of replies.
It will never going to be easier for your upcoming campaigns too.
Because, you are not considering early applicants and your own rule of
minimum of 5 Merit in the last 120 days but you select applicants with 100+ merits (or at least 40+ merits in last 120 days). It is a good practice to give some time so that people from different time zone will apply but your merit requirement is misleading at least in my observation.
With all due respect I like to suggest to be more transparent with your rules for your campaigns like you may unveil what you actually look from your applicants. I guess it would be more appropriate if you set your rule like people with 50+ merits in last 120 days only need to apply so that you may not get 6 or 10 pages of applicants.
There are obviously a limited number of spots. Any campaign manager will choose the objectively best candidates for the slots available so that both the subject company and perspective companies will see positive results from signature advertising of the campaign.
Any merit requirements are minimums to even be considered (this is my presumption). If there are enough people who have received 50 merit in the last 4 months to fill the entire campaign, chances are they will fill all the available spots if everything else is equal.
If you have very low merit, chances are hiring you to advertise would not reflect very well on the company paying for the advertising, nor the campaign manager.