i am giving you my humble views from 3 aspects. RELIGIOUS ASPECTs (i) 25 years in AGCC and working mostly with 95%) with local Muslims has given me more exposure to Islam than 95% Indian Muslims. Mind you these local people are all genuine humans just like us in India, friendly, trusting, caring. (There are exceptions like in any society). You can't have a proper ISLAMIC NIQA sanctified by a Qazi unless both are Muslims and mohar is declared+ accepted + PAID. Islam allows Muslim men to cohabit any number of non-Muslim woman subject to owning up responsibility for the children born from such cohabitation. But they cannot marry more than 4 Muslim women (concurrent wives). Of course, there are many restrictions before taking a second, third and fourth wife. LIKEWISE, A TAMIL BRAHMIN wedding calls for VARA PRAVANAM= declaring lineage for at least 3 generations (ideally 7 generations so that same gene stock marriage i.e 23rd chromosome is cross pollinating) of both boy and girl. If the boy's side's lineage is known )i.e in case the boy or just his dad converted) and elders were in Hindu fold and gothram details are known, then the same can be extended. However, the Goddess Lakshmi is invoked in bride and bridegroom is declared as Bhaghavan Narayana and bride's father offers Lakshmi to Narayana as kanyadhaanam. Will the Muslim boy accept to these mantras as first tenet of Islam is that there is no God but one GOD. (ii) In Islam, Mohar is paid for the girl to take care of herself for the IDDAT period (i.e 3 months after divorce or widowhood - minimum to make sure that she is not pregnant) before remarriage. If she is found pregnant during the IDDAT , she can marry if her next husband is ready to legally accept the child she is carrying as his own. Otherwise, she must wait, deliver the baby, ensure either her parents or siblings or her EX-husband's parents are siblings agree to nurture the child and then only remarry. In Hindu Brahmins, we have mantras right from conception to delivery , to punyajjanam, Naama Karanam, to mundanaam, karNa bhooshanam, abda poorthy auysh homam, upanayanam, vivaham and all the way to marana samskaarams but no mantra for divorce. IN OTHERWORDS, EVEN IF SOME PUNDIT / QAZI is ready to solemnise your marriage, there is no religious sanctity either from Islam or from Hindu. My suggestion is that you should take religious route only if you do it to find some satisfaction of having done that (i.e eating half plate is better than eating full meal!).
ASPECT 2: Arya Samaj wedding offers an escape route and there are people in chennai who will conduct the marriage in that style. I have no clues on their compliance requirements. You can google and find out. That will give you a satisfaction that you had a religious wedding. Likewise tribal customs allow community marriage where the families together share the wealth / expenses and sense of security AND ALSO individual marriage where the husband and wife resort to their own pre-agreed conditions before marriage but lose the sense of guarantee from elders to protect them in case of any misunderstanding