If there is no one to check your mail and look for the oath letter, then I suggest (if possible), to get your mail forwarded to an address where someone can check for your OL. They can then let you know the oath date and if you are not back, then can send the OL back requesting for reschedule.
In case there is no one to check your mail or to forward it to someone, and you miss your Oath date, then I think you can make an infopath after you come back, and try to reschedule at that time. I will be very surprised if they would consider your case as abdondoned. You are going to be a US citizen, a person who can vote, and these goverment officials need your vote so they will be nice to you and will accomodate you.