Using DNSCrypt will encrypt DNS queries and responses from your Tor relay to the DNSCrypt resolver. From that point on you do not know and cannot control how the resolver is going to do with DNS queries. And you don't know if that resolver uses Google or is compromised or is malicious etc.
Why not route all DNS queries through Tor for "Plausible Deniability". The nuts and bolts are already there in the client.