When you talk about extra support staff for "marginal" students, keep in mind that many of these students are just as bright but through no misdeed of their own have grown up in families where no one went to college and attended high schools where rigor was sadly lacking. They come to college with weak skills and poor comprehension of college culture--there is one.
I recently listened to this excellent This American Life podcast which gives a glimpse into the lives of excellent students at a poor high school and their struggles with attending college.
I agree that these kids need support and help, but I wonder about the best way to provide it and if tossing them in as full-time first semester freshmen who may also be far from home is the best approach. It's almost like setting them up for failure: everyone you trust and care about is hundreds of miles from here, everything is new, the workload may be geared toward tiger cubs, and you have no idea how to deal with situations that are second nature to your classmates. On top of that, you may also have no clue how to deal with financial aid requirements like renewing stuff or signing stuff that you may completely unaware even exists.
IMO, a better way to help these kids might be to put them into a one-year gap program that helps them learn how to survive in college. If I was designing something like this, I'd give them a class on how to use a library, on how to deal with financial aid, on how to buy cheap books on the internet or borrow them at the library, and on how to manage time. I'd also enroll them in onsite classes that would require them to use the library to complete assignments. They might also have an onsite part-time job (10 hours a week-ish?) to help them learn to manage money and save for next year. Ideally, the program would be local but residential from Monday to Friday initially, so that they'd be away from home during the week, but not too far from home, and not for too long (maybe not residential the first week, either). Then later, they'd be required to stay for a weekend here and there.
There would be field trips (e.g. museums) and community service days. Community service projects with seniors from private schools might help kids get to know each other.
Okay, back to reality.