If you put the battery low in the boat and just forward of the mast (in the forward cubby area but as far back as possible), I think you will like what the extra weight does. Since you now have large diameter wires running a good portion of the boat length, it is really a good idea to fuse. But. you may have a problem with the 10 gauge wire.
If that is around a 30 pound thrust 12 volt motor, I believe the peak currents will be in the 25 to 30 amp range. You REALLY want to fuse a large wire run like that running inside the boat (large wires are good at starting fires). If you look at a chart for wire gauge vs current like this
http://www.cerrowire.com/ampacity-charts, 10 gauge wire is only rated up to about 30 amps. So in order to protect the wire, the fuse you need to use would be 30 amps or less.
But that is also right about where that trolling motor could have peak currents. So the largest fuse you should use is really a little too small for that load. Six gauge would be a better choice as you can use up to a 55 amp fuse and that should not false blow when using the motor but should protect the wire in a short. Four gauge might even be even a better choice.
Why have a trolling motor on a small boat like that? I once saw a small sailboat with no motor hold up a launch ramp for about 20 minutes because they were having all sorts of trouble sailing off the dock (on shore winds). This held up a bunch of other boaters from using the launch ramp.. I dont think the sailboat that held everyone else up did much to help the respect issue between sailboats and motorboats.