If you have the integrated brake controller, the computer will KNOW when you plug in and who knows what it stores after that?? You can program it for multiple trailers and the computer will keep track of the individual miles while that trailer is connected.. Seems to me, it'll also record what mileage the truck has when it's connected??
I'd just wait another week.. I'm sure the dealer can keep your trailer for you and you just take some 'scenic' roads trips and get to 1000 miles and hitch up and don't fret about anything after that... :)
If it's YOUR schedule that is the issue... Well, there you go.. ;)
Mitch