Capt. Caveman may have experience or he may not. He is right about a dog walking in a flat area or neighborhood and walking the first month on the AT. It is a different experience, my dog loved hiking. I have an old lab that used to section hike with me the first 100 miles or so of the trail. We would only go out for 4-5 days but they always took a toll on him. The last time we went out it took him a couple of weeks to recover. Just make sure your dog can handle the miles, weather, etc.
Rocky 65. I’m 10 years younger than you. Starting in March can be tough on anybody, I would not start before St. Patrick’s Day March 17th. It can be snowy, cold and icy before that time. It will be cold after that time but usually only at night. Having a dog along during that type of weather can be tough on both of you.
If splitting the load is the reason for a partner, stove, filter, tent, etc. You might want to reconsider. Your speed is not the problem. A partner may back out (sick,injury, work etc.) at the last minute. You would be stuck. A partner may decide to give up the first week, you would be out of luck. Injury on the trail etc. happens.
I would suggest going very light weight and carry your own equipment. Even the best of friends, marriages etc. run into problems if one of them can no longer carry on. You need to be ready to carry it all. You should have no problems in getting your pack down to 30-35 pounds with food and water. If you cannot carry that amount of weight, you may want to reconsider the hike. It is difficult. No matter what speed. Good Luck to you.
Bilko