Supernaut: Greetings neighbor, not that far from you. Yes, going to the external port would make a big difference. This is like installing a larger battery in a vehicle as compared to using a smaller one. I did this when I had my WildView EZ Cam trail cameras. The barrel plug which fits in the external camera port can be purchased at The Source (formerly Radio Shack), an electronics store or Princess Auto. This part may have a transformer (the part that plugs into the wall). Just cut off that section. You may even have this part from a rechargeable tool, Attari or some other rechargeable device that no longer works. These can also be found a Pawn Shops or Garage Sales. The centre of the barrel plug is positive and the wire coming from it will have either: 1)a white tracer or 2) a grey tracer or 3)a dotted line. This wire will connect to your positive battery terminal. I marked this wire with a white tape with a (+) on it for quick reference. Hooking the wire up to the wrong battery post will fry a component in the camera which prevents the external port from working. The internal battery section will still work.
Another idea that will work in cold weather is install Lithium Ultimate batteries. These are high voltage, testing 1.79 to 1.83 volt fresh out of the package. Other forum members have recommended them for cold weather use as well. Any battery testing 1.0 to 1.2 volt, the camera will not function properly, or not at all. In my case, the WildView had a 12 volt external port. I did not let the battery get down below 5 to 6 volt, where it would be changed out, the removed one would be taken in to warm up over nite, then recharged. I purchased the 300 series Energizer from WalMart. This series is more expensive but has higher cranking amps. Lifting this battery, then lift the 100 series, you will find the 300 considerably heavier due to more plates in it. I don't have a manual at home, but I believe Bushnell external port is for 6 volt. Good luck.