How to prevent ruining my retainers from clenching my jaw at night? Mouthguard + retainer?

I don't grind my teeth but clench my jaw, and I notice some impact points on my retainers. How can I lessen the impact on my retainers at a low cost?

I heard of specifically made night guards that place of my retainers, but couldn't wearing something soft and thin like this be a solution?