You can not have any "sham" Nikkah...
Unless I guess if it's a contract marriage by the court...but as far as I know..it won't really be considered a Nikkah..
In Nikkah, the bride and groom have to say Qubool Hai 3 times.
I think even in Hinduism, the Sindoor, Mangalsutra and Phehre are considered shaadi..nothing as a shaam... it could be incomplete without each rasam..but the purity, importance and reality about the meaning of those wedding rituals are not incomplete.
Both in Hinduism and Islam, you can get married without having all the other rasms like haldi, mehndi etc... but Nikaah (in Islam) and Mangalsutra,Sindoor,Pheras (in Hinduism) are essential
Oh and you have to have a Maulvi/Qazi or Pandit in both cases.
Also, if you are registered as a married couple in court ..you will still not be husband and wife until u get Nikkah done