I do floats ina solo canoe and that can have little more room in it than a yak. But I do try to approach the whole thing like I was backpacking. If on more than an overnighter I don't take things that need to be refridgerated. With the exception of maybe a couple of steaks that have been frozen. Wrap in a little newspaper, plastic bag and then a towel or 2 and some clothing. Makes a great 1st night campfire meal and will keep a couple of days like that in cool weather. I also often take fresh veggies like corn, carrots, beans, and potatoes. They will keep fine just open in the boat. I do take canned goods. If you want alcohol enjoy bourbon instead of beer. It packs better. For water I usually go to the grocery and get one of those 2.5 gal spring water cubes with a spigot and a handle. Doesn't take up much space and is very convienient. I actually use these alot when camping either out of a vehicle or canoe. I also carry 2 Kleen canteen SS water bottles. This pic is from a fully loaded 4 day float a couple of years back. Tent, self inflating sleeping pad, sleeping bag, backpacking stove, clothes, tackle bag, 3 rods. I have a double milk crate that fits behind the seat which holds the above mentioned water and canned good and any loose stuff I might carry. 12' canoe.
I'm thinking of trying one of the new collapsible tent cots for my sleeping quarters. This should be nice on rocky gravel bars.
Probably more than you asked for but I take stystem approach to boat packing.
KISS Principle = Keep It Simple Stupid.
Your best defense against Murphy's law!