I have to concur about not brining any military items -- seabag, utilities, etc... She will be issued those items, and even if she took them, they'd go in cold storage. They will, however, be useful later once she leaves MCRD.
On the exercise and weight thing - backing off the weights would be a good idea and instead focus on body weight exercises -- pull ups / flexed arm hang, dips, push ups, sit ups, rope climbing (this is a big source of failure for many recruits). These are the types of exercises that she will be doing at MCRD. As far as weight, if she is in good shape it shouldn't be much of an issue. Increase cardio workouts and cut back on weights -- things will balance out in recruit training because the rate at which she burns calories will definitely increase. The only way that she will get sent to the fat body platoon is if she is not able to keep up physically. Other than that, they may restrict what she can put on her tray in the chow hall, but that is about as bad as it would get.
I'll do some checking on what
gear is allowed, but she should be getting something either from her recruiter or from MCRD.