Rural housing loan question?

My husband is disabled and we have applied for the rural housing guarenteed loan program in the state of Maine. It is with the loan underwriter now. Does anyone no if not having any new credit or collection accounts(Paid off) will hurt our chances? I got his middle score up over the 620 mark and we have one acre of land already set-up w/septic & well and an older trailer to trade in. The reason for the collection accounts is because it takes FOREVER to get approved for diability. I also did not want to open new lines of credit so our debt to income ratio would be o.k. This getting a new mortgage is scary to me & I wanted to know what other people know about the program, their ideas -good & bad! I can take it! Thanks!