The Alpacarafts are great, but hauling a moose in one......probably not so great.
For a boat you could carry internally, I'd consider one of these:
http://pakboats.com/pakcanoes/ My crews on the Yukon Flats used these things day in and day out, dragging them on nasty portages, folding, re-assembling, etc. I'd consider one of the 15 or 16 foot boats, depending on how many people you'll have.
BUT, if you feel the need for a hard boat, I wouldn't worry too much about it. A 16 or 17 foot canoe should work fine.
Caveat: I know NOTHING about Canadian or BC regulations regarding carriage of external loads on fixed wing aircraft.
The Alaska guidance suggests carrying one boat on the right side vertical struts. I never did so, unless I was carrying two canoes. I prefer to have the boat on the pilot's side of the airplane where I can SEE it during a flight. On the passenger side, can't see it.
I attach a canoe with good quality ratcheting straps. Get good ones, like these:
https://www.cargoequipmentcorp.com/1-In ... Wire-Hooks or similar. The hooks on these hold well.
Figure out where you want the canoe on the struts, to keep it as far forward as practical, but behind the propeller. Strap that sucker down tight, and tie off the bitter ends of the straps to keep them from flapping. If the straps change the shape of the canoe, they're just about tight enough....

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In flight, you probably won't even know it's there after a few minutes. Yes, they induce a LITTLE bit of yaw, but it's surprisingly minimal. With external loads, I always try to avoid any big climb angles, and keep airspeed under control during descents, but really one canoe isn't a bad load at all. Don't forget to count the weight of the canoe in your load calculations.
As to a 700 mile flight, it can certainly be done, but that's a long haul both coming and going. The boat will slow you down some, but not massively, maybe 8 to 10 knots on a 185. No experience with 182s on floats, so can't say, but it'll be in that range, I'd bet.
Before I took on that long a flight, I'd borrow a canoe and try a local flight first, and see what YOU think. Then make your decision on whether you want that thing out there for 700 miles.
I've carried a lot of external loads, and GENERALLY, canoes fly just fine, with just one boat aboard. Two canoes, not so good.
BUT, if there's a reasonable way to use one of the folding boats....I'd go there. Depends on whether you're planning to buy a canoe or you already have one. The PakBoats are tough, and they paddle fine. And, they'll haul a load.
If you want to talk more about this, send me a PM and I'll get you a phone number.
MTV