I think your main worry will be close family and their attitudes.
I know of a couple who I believe are still jw's who eloped in the middle of the night in the early 1980's, went to Gretna Green and married in a civil ceromony and came back to the hall. Fait Accompli.
I know another jw couple who did the same but went off to Paris!
All they got was a verbal bollocking but no reproof or anything. The last couple - he became a pioneer a year later and then a few years after that MS then Elder.
As far as anyone knows the above couples had "clean" courtships in jw terms too. Just didn't want the hassle of a formal jw wedding.
Also I knew of couples who were "dealt with" by elders for sex before marriage and so not allowed to use the KH and so had a civil non-religious ceremony.