A maximum of two legal dwelling units per parcel of land may be approved forseparate individual short-term residential rental unit permits.

How do I put four individuals on one lease?

I have read that I can file trespassing paperwork for the individual in the trailer.

But that might be per the individual lender.

Will a lender need to review our individual credit history/worthiness? 

Right now I am looking into a structure like this:-Borrow from an individual with an IRA -> convert to a SDIRA-Make loan interest and principle payable at the end of term (because it's an IRA)-Structure similar to a construction loan with monthly drawdowns of about $5k for the highest probability of success with direct mail-Possibility for an equity component: pledge a percentage of profit along with normal interest in the promissory note (a joint venture)Would this be attractive to a potential investor considering I am wholesaling in California and the average fee is $15k-$20k on the lower end?

I'm open to investing in syndications but don't know if that is better than investing in individual properties at this point. 

If you are a systems oriented individual, then create your system.

A real estate professional is one who:(1)works 750 hours or more in a real estate trade or business in which the individual has at least 5% equity and materially participates, and(2)more than half of the services that the individual provides are in a real estate trade or business in which the individual has at least 5% equity and materially participates.For your common, non-equity W-2 employee who works full time, this makes it not impossible to qualify as an RE pro, but highly improbable, as your average full-time employee works around 2,000 hours in a year, give or take. 

Even then you have to do the legwork up front to vet the sponsor and individual deal.