How many people in the canoe? How long are you going for? How much gear will be in the canoe? And yes floatation strips all along the boat under the gunnels will help stabilize the boat when swamped. 34 feet is just over 10 meters, so you would get just around 75kg of "floatation" on each side of the boat. Minicell foam strips, 3x6x34feet would be better then the noodles, but more expensive, but would last a lot longer and I'm sure a lot more "floatation" from it to!!
If there will be empty spaces not occupied by paddlers or gear some kind of center bag flotation would occlude the most water, and make bail or pump out easier.
With a 16 seater there could be some big voids to occlude with a smaller crew. I have paddled a Clipper Mariner with 8 people; bow man, stern man and three pairs seated side by side, and even that 22 footer would leave a lot of wide, deep space to fill if not occupied by paddlers or gear.
One very old school trick. Back in the day my father DIY’ed center floatation for our Grummans using a huge block of Styrofoam. He painted it with something (latex paint, IIRC) to prevent the awful Styrofoam squeek and to make it more durable. I’m not sure there
were float bags in the 60’s, but given my modern day druthers I’d rather have bags than a giant Styrofoam fugly block.
OK, getting really off the wall. If transport space isn’t a issue, maybe a couple or four cheap plastic ice chests, with the lids taped or glued shut. Fill them with foam, empty plastic milk jugs or etc and tie/strap securely into place. Probably the least expensive solution. Camp seats or side tables when removed.
(That might be the best use for cheap, poorly insulated ice chests. I’ve upgraded ours several times and wish I’d just bought a good one to start with. I’m sure there is a cost delta formula; purchase price + years of melted ice cost + bought a better replacement cooler + bought yet another really well designed cooler = cheaper to buy a quality ice chest to start with)
OK, off the wall Part II. Minicel is pricey, especially in large/long buns. Shipping costs add considerably to that. Best deal ever on minicel was a huge box of wedge shaped chunks.
Free. From a friend in the kayak manufacturing biz that used minicel bulkheads, the wedges were the scrap leftover from cutting oval bulkheads out of minicel rectangles.
Got a kayak manufacturer in your vicinity? Methinks they just throw those minicel scraps away and they might be ideal for below inwale sponsons.