I made a video that shows how to sex a snake using the Palpation method. It's demonstrated on a Brazilian Rainbow Boa, but should work on your Kenyan Sand Boa too.
Basically, while supporting the tail of your snake you run a finger from the vent to the tip of its tail. If your boa is a male, you should feel 1-2 small bumps which are the inverted hemipenes. If you don't feel any bumps, the snake is a female. It takes a little practice to find the right amount of pressure, but it's pretty straightforward once you get the hang of it. Let me know how this works out for you.
I tried to feel. I can definitely feel a bump, but only one. Even though I only felt one you still think he's a boy?? If so, very informative video! Thank you for sharing!!
Dawn
1.0 HIB (Cinder)
0.1 KSB (Vicious)
0.1 American Warmblood (Moo - Sudden Eclipse)
1.0 Oldenburg (Nova - Saint Supernova)
0.1 Doberman Pinscher (Tira)
0.1 Miniature Pinsher (Bitty)