I have the same boots and LOVE them.  I have hiked eight consecutive miles in them and was comfortable all the while.  

If you have a chance at  fully submerging the boot, just cinch the strap at the top and very little water will pour in.  

If your feet get warm slip 'em off in the boat and go barefoot.  I will say this, they don't provide much ankle support which I know is a requirement for some.