No reply means no validation, meaning not allowed. There are stock or validated mod alternatives you could've used. The argument about extra mass you carried doesn't have any merit, as the accepted mods must work equally for everyone, regardless of any individual self-penalizations. Personally I wouldn't really care much for 0.1t per kerbal less mass the ALCOR has - but that's not the point. The point is that you didn't adhere to the rules of the challenge, even if you didn't get any benefit from it. Therefore unless Ziv says it's okay, I'm gonna assume it's not.