We really haven’t had that serous of a problem like you have but here is what we do. All members have to have at least a total of 30 Community Service and 30 Fundraising hours to participate during the build season. Then during the build season they have to have a total of at least 80 hours to go to Regional and Nationals
We call community service is spreading the word of FIRST. For example: parades, presentation to Boy Scout troops, demonstrations at the library, mentoring lego teams
Fundraising hours is explains it self. Brat Sales, Spaghetti Dinner, and Concession stand at local events
Many teams explain all this in a handbook.
Many links to examples to handbooks can be found
here and
here