Hi Simeon, I had a similar problem with my Anatolian except he is the size of a Great Dane!!! and I live in a town!
He is now nearly 11 and the last few years has calmed down alot, but when he was around 4/6 he was terrible with other male dogs, especially a GSD/Rottie who was a guard dog at a local wood yard. They hated each other on site and there was no way we could walk them past each other. If I walked him past the yard his hackles would go up so much that he had to shake when we got past to get the fur to lie down again!
I am quite a strong woman but I have always used a halti on my dog, I clip the lead to the collar first then through the ring on the halti, this stops the halti riding up.
I took him to a brilliant training class all his life, but it never cured this - he is brilliant with people, kids, bitches and anything that is not a threat, but show him a male dog that wanted to take him on and you could not stand within two feet of him. It is just his nature.
Your dog will grow out of it as he gets older, but I would not unduly worry about it, as long as you make sure he cannot get to the other dog and you are in control of the situation. I used to muzzle my dog if I took him into crowds of people (round shows etc.), but like you I need him to be able to defend himself if he is attacked (as he has been a number of times).
Like I say, it does not sound to be a major problem for you as you live in the country, but I would muzzle him if you take him places like a vets waiting room etc. where there could be other male dogs. Also if you go to a training class then pre-warn them why you are going so that they can make sure any male dogs are out of the way and under control.
Good luck, enjoy your dog (I went past a GSD today with my dog and in years gone past he would have been bouncing up and down, now he just looks - I almost wish I had those years back!)