So campus placements started in 4th sem only? Don’t they usually start in 6th sem? Even otherwise, they must go on till 6th sem end for you, isn’t it? If yes, you can clear the backlog by then.
In my times, many folks having current backlogs, had appeared in Infosys drive, hiding the backlog, and some of them had never got caught. Some who got caught, had their offer revoked very close to joining. At the time of recruitment, they hadn’t checked so closely. If your college doesn’t stop one guy getting offer, from appearing in any future campus drives, then I think it is a risk worth taking. Get an offer, and clear the backlog and get another offer. Whichever works, go that way. But be mindful that if companies find this lie even during training period, or even after that during job, they may fire.