I was backpacking across south east Asia for 4 years. At one point I crossed the border into India without a visa. I meant to spend a few months there and thought it would be easy if I just got lost in Goa.
Turns out I couldn't get a hotel/guest house room anywhere without them checking my passport.
I got arrested after a week and ended up spending 3 weeks in jail. All I can say is: don't.
I'm on their blacklist now, I have to have special permission to be able to travel through India