A total cost of 6.3Mn over 23 units equates to 274K/unit...this appears unbelievably low for San Diego...I'd want to see full development budget detailing hard, soft and financing costs as well as month by month projections showing construction and lease up cash flows.What's the 2.2Mn purchase price for?

Look at the trailing 12 month's expenses on the seller's operating statement. 

Or what I would charge for rent.

The extremely hot summer has subdued the demand this month though.

Or find a local design firm that has done cabins where they can show you proven rent results from cabins they've designed and have them charge you by the hour. 

While preferred returns sound appealing, they are often not realized as monthly cash flow.

By way of example, a lender may charge retainage, only release soft costs upon C/O, may limit loans to a set number of draws or only allow draws once a certain dollar amount of work has been completed.

good luck - 4 months review at least from what I learned.

An example, a small down payment initially, but the note has now seasoned for 60 months with on time payments documented by a third party servicer.

Plus they’d be collecting late fees I assume you’re not charging.