Checks,
I don't save dining receipts either (since I don't drink, I almost never spend more for food than the standard meal allowance). All you need is a means to prove which days you were at your unit (flight schedule or something like that), then duduct the standard meal allowance for each day you were there.
Where you stay has no bearing on the meal allowance. Just don't try to be tricky and try to claim you were paying your relatives rent while you were staying there (unless you really were and have receipts to prove it). When I go to drill weekend, I get a free room at the BOQ since I live more than 50 miles away. This doesn't reduce the amount of food I will eat over the weekend. The IRS doesn't know if you are getting your free room from the unit or your family.
Also, make sure you don't claim the days you were on det and got per diem. The only exception to that is if you get stuck with the Navy's 'Smart Per Diem' where you only get some amount less than the standard per diem rate. If that is the case, then you can deduct the difference.