On the HARRISON River, not the Fraser, a buddy of mine has fished with me using his 10' boat with a 6 hp motor. I've used a 12' boat there. But I haven't experienced the big winds that I hear can occasionally occur on the Harrison River. This would be from Kilby launch. Uh, if you have to cross part of Harrison LAKE to get to the Harrison River then I'm thinking 16' minimum, and no big wind forecasted, especially for your return trip which might be hours later.
We had to TOW a 12' inflatable downstream on the Harrison River one year because his motor went out and the wind actually blew him upstream enough that they couldn't make any progress downstream (in the lower-current areas). Wow. Bring a backup motor.