Have you tried freezing the Kongs? Here's what I do --- soak his regular kibble in water until it's mushy. I also add a dollop of yogurt or peanut butter and some freeze dried treats (like liver). Shove a baby carrot in the small end to seal and stuff the Kong with the mixture. Freeze overnight. We have four Kongs, so always have at least one frozen one. When Archie has one, I subtract some of his dinner to account for it.
Both of mine liked Himalayan chews as younger pups, but yours sounds like a more intense chewer, so I'm not sure. May be worth a try, though. They are not as hard -- I won't give them to Archie (who is three) anymore because he can completely destroy one in 15 minutes, and they are on the expensive side.