They did offer to get a Co-signer and they're willing to pay 3-6 months in advance.  

A co-worker of mine used to live in this mobile home but then she and her husband got a job as "ranch managers" and moved onto the ranch.

They brought up that if I had a co-signer that they could lower the interest to 7.375, so I decided to bring my father in on the loan, but because my credit didn't qualify alone for their program, the problem is they want him as a member on the LLC.As of now, I am the only member, and with this change I am concerned for the following:-How can this affect my taxes, and business?

My sister-in-law is a co-owner of this property, lives on site and functions as the Den Mother keeping the place in-order.As you mentioned in your post, lenders are not warm-and-fuzzy about a renting by the room (even though we use written leases).  

Recently got put on to Bigger Pockets from a co worker.

It sounds like you're doing well in looking at their cumulative picture.I have used a co-signer, typically a parent, in the application process.

Maybe you arrange a co-investment with them or you do some of the work they need done, although disposition of loans is not a short term project so this method would have it's barriers to expose concepts to you which are unknown to you.

As for tenants without rental history, you could ask for a co-signer such as a parent just to protect yourself.  

I believe it is California law to have a CO detector installed but I believe you only need one CO detector, but you do need smoke detectors near all bedrooms hopefully the bedrooms are close enough together that you can use one detector for multiple bedrooms. 

Since the job was new and we knew this was higher risk on several levels, we have a co-signer.