To what I can contribute to: our team typically only allows pit crew, judge speakers, and safety captains in our pit at all times. Of course on day 1 there are usually programmers and scouts posting schedules in the mix. Team members, if not scouting, are allowed to browse the pits and visit ours, but as soon as the pit becomes a "meeting spot" someone brings up the fact it's getting crowded and we disperse. I feel like this is related to rookies not knowing that just like during build, there are a multitude of positions during competitions.
Our team doesn't have that many students involved in sports, mainly things like speech/theatre/music. (I'm in like 5 clubs but that's Another Story.) As long as that member lets the mentor know where they are going and how many days they cannot attend build, and don't sit around when they can be there, it's been fine. We also have a 60% attendance requirement to go out to our week 1/2 regional since its considerably further than our second one. Also, not to point fingers, but are your mentors aware of this issue? It always helps when they realize it too.
I remember there being a video 1114 made about team management? I think
this is the PowerPoint link. Feel free to PM me OP, I have a bunch of safety guideline sheets we use for going to competitions. :>