As a breeder who also has stallion(s), I'm going to say GELD him before he gets any ideas and forms bad habits. Cryptorchids or Ridglings are (AMAZING! Horse Forum and spell check doesn't recognize those 2 terms!) majorly flawed and should not be bred on. I'll even go so far as to say, if my stallion had 1 crypt by one mare that may be a one off thing, but if it happened twice or more with different mares, that stallion would become a gelding because HE would obviously be the problem in the equation.
As a stallion owner/breeder I will tell you that logistics become very difficult when you have mares in heat, a stallion and limited (20 Acres) space. If you really want to breed, buy a couple of TOP QUALITY(very best you can afford) mares and buy breedings to proven stallions. That way you still get the foals and you don't have to do the horsey shuffle on short notice.
Quick little example: We are under severe weather warnings, possible tornadoes & large hail and frequent cloud to ground lightnintg strikes, today. I had a doctors appt. in the city this morning so decided to stall them all until I got back so I didn't have to worry about injuries from weather. Stallion is in his nice, sturdy stallion stall and I called in all the girls. Two of them we had just teased last night and their reactions were, "HO HUM, where's dinner?", so ok to stall next to him. This morning? Both ran up to his stall and said, "OH HAY BIG BOY! Whatcha doin'?" and indicated their willingness to give him something to do. I ended up shuffling the stall assignments to make sure either pregnant mares or geldings were right next to him. Made me late for my appointment. I wouldn't trade him for the world, but sometimes.........hormones.