unfortunately, Marketo does not have a solution that allows you to set a maximum number of leads for a trigger or webhook (which is by definition, a trigger!).
does anyone in the Community have any creative ways around this?
Hmm, well... I am the adventurous sort so I would probably run everything through my proxy server and do the counting there. I guess short of that you'd have to tell them to program in the maximum. What is the reason they don't want all the 'hooks to hit their server?
Don't know about a trigger, but if you control the webhook, you can keep a counter on the webhook side and then return an error after n number of requests. Of course this won't stop the webhook from being called, but it will stop it from modifying/launching anything.