Sani Longivity

My family and I are going to a cabin in big bear for the week of Christmas and I'm going to bring my kegarator and three of my latest homebrews to share. I'm also going to bring some empty bottles to fill up if some of the family want to take some brews home to enjoy later. So I thought that it would be a good idea to fill one of my extra kegs with sanitizer (idphor) so I could easily sanitize the bottles before I fill them up.

So I'm asking the all knowing collective minds of HBT how long does sani last, or if eve goes bad? And if this is a good idea or is there and easier way?

Thanks guys

Seems like it would be a lot less headache to just take some sanitizer and a bucket... mix it there right before you need it...