Minor - P4 The first issue is that "clusterAuthMode" is allowed via the --setParameter option on the command line:
$ ./mongod --sslMode allowSSL --sslPEMKeyFile jstests/libs/server.pem --clusterAuthMode sendKeyFile --setParameter clusterAuthMode=sendX509
Results in the server starting with:
> db.runCommand({"getParameter":1, "clusterAuthMode":1})
{ "clusterAuthMode" : "sendX509", "ok" : 1 }
The next issue is that "sslMode" is allowed via the --setParameter option on the command line, but it's broken for a different reason:
$ ./mongod --setParameter sslMode=allowSSL BadValue Bad value for parameter "sslMode": Illegal state transition for sslMode, attempt to change from disabled to allowSSL try './mongod --help' for more information