I agree that rail fence is a good pattern for boys and men, as long as you avoid floral patterns and the colors pink and lavender. I can imagine a fun quilt using a camo print and some coordinating fabrics.
While it's a little bit more work, I encourage you to try the hexagonal One Block Wonder idea. Because the design becomes so cut-up and rearranged, all that matters is the colors of the fabric. (You never need disclose the pattern of the "original fabric.")
As for colors, I find that men are most comfortable with browns, greens, blues, grays, and black. Most other colors (tho not pink and lavender) are very acceptable as accents. White and beige are also very acceptable and can be used liberally - as long as they don't dominate.