This type of project here is referred to as a JADU (Junior Accessory Dwelling Unit), since it is attached to the primary residence it is classified as a JADU as opposed to a traditional ADU (Accessory Dwelling Unit). 

Having some private money at 8-12% annually that can be accessed quickly may be more advantageous than working on a deal with traditional financing with a bank/credit union when they want to due a pre-renovation valuation/appraisal and post-renovation valuation/appraisal and then go ahead and set up a draw schedule to align the funding with the project timeline and any inspections of the property... 

Which is fine.Then, when they’re on one side of a traditional sale and they want to justify either their clients offer or the list price in this small, historic part of town, they post the off market deals retroactively with the listing description as “comp only” to MLS and all the websites (Zillow, Redfin, etc).I know this because I was a buyer represented by the son on a house that eventually fell through post inspection.

You are better off selling via a traditional deed of trust and note.There are no benefits to a land contract in Maryland and only cons.

Traditional financing a reasonable timeframe would be in the 30-45 day timeframe. 

Traditionally we have invested in a few regional markets in the northeast that we are very familiar with, but recently we are looking to expand outside of this market.

However, in exchange for more responsibility, you also get a lot more control over your investment than in a traditional stock, where your only control is to own it or not.Real estate is a concentrated asset.

I may have jumped the gun on quitting my W2 job and starting my own handyman business as far as traditional financing goes.

I am a commercial lender but if I were you, I would look into getting a HELOC on your house from a traditional bank.  

They're not like traditional 30 year fully amortizing loans.