Well, I would agree to drink water and deal with peeing, but it's NOT an easy thing getting out of your boat to pee in the water. Not even remotely comparable to getting off your bike to pee in a cornfield! I wouldn't even attempt getting out of my boat in the water unless there was another kayaker whose boat I could use to brace mine while I get back in. And I don't recommend anyone trying it unless they've at least had a little training in rescues. You will have your BF with you, but do both of you know how to get you back into your boat once you've gotten out (or even how to get out in the water, without capsizing)?
Pee in your pants if you need to. You'll be washing your boat out and changing your shorts at the end of your paddle anyway...