Request for Evidence (Continuous stay)

[Al Bundy 2]

After getting an immigration visa, I arrived in the US with a temporary document with an instruction that I should complete the process and get my green card through the nearest field office. Within 3 weeks of me arriving, government shut down for about three weeks. I was unable to get a social a SSN or the greencard. I ran out of resources. I decided to return to my now former home country to sell off all the assests I had and have a cushion of funds as I start. I stayed out of the US for 9 months. I applied for neutralization and during the interview, I was told to produce evidence that I had not abandoned my green card as I was away for longer than the allowed 6 months. Since i did not have any documentation to do anything in the US (green card or SSN), I cannot provide any paperwork such as letters or bills that show address of abode, taxes or employment records. Additionally, I was staying with a long time friend and had a verbal agreement to be contributing towards rent. How do I show continuous residence without having a paper trail that proves so?