Think where you would want them in case of fire...
While I have a 410 not a 356, I think the thought process about the locations should be similar. I have one inside the door to the forward cabin - if you are sleeping up there and a fire breaks out further aft, you want the extinguisher at hand. Likewise, I have one inside the aft cabin. Finally, I have a third just inside the companionway entrance - it can be easily be reached from the cockpit or from the galley and thus is handy both for outside fires or for engine or galley fires. Don't be cheap about the saftey of you and your guests. Get enough to have one in each likely place you would want one, and HANG THEM UP NOW!