My solution, given the time frame, would be to double dose ferts (possibly split over the two days before leaving) and go have fun. And if I was feeling really, *really* inadequate, I'd do another W/C after I got back and start over with the dosing.
My feel on this is that unless you have a truly high-light tank that requires daily tweaking, there's no need to overthink things. Just double up beforehand, maybe with a waterchange thrown in, and go enjoy life.
We often have the urges of those parents that everybody seems to be covertly critical of. You know the type - their kids can't possibly survive unless they're there 24/7, and if they leave for even a moment, something horrible will happen.
Planted tanks are generally like most kids - you can walk away for a (short) quiet smoke, and when you come back ...they won't even notice you've been gone.