I have tried reaching out to several listing agents that say the seller is motivated or that seller financing is available and they either never reply or they have terms that require a large down payment of 20%+.

Take out a $250K HELOC and buy a fixer upper large duplex in a good area.

Use a low down loan such as fha to purchase a property in the areas you listed with the large lots you listed.  

Someone mentioned the 1% rule, however if other expenses such as property taxes or maintenance are large, it might still not cash flow.Every deal needs to be analyzed in its own right to see if you're comfortable with the risk/return.  

From what I know, the common process of financing in the real estate development is like this:https://cdn.corporatefinanceinstitute.com/assets/p...But what if a junior developer who has less job experience in this field than any others and is trying to develop a huge scale of townhouses?

By and large the 'problems' have been the same: inherited tenants!

In regards to out of state I would also recommend SCALE. 

Gibson unless you are very game for a challenge then for your first deal I wouldnt take on the risk and the headache of new construction or such a large rehab.

you know some of these markets are flooded with rentals.. and it could be market symptoms.. everyone and their brother has been buying sfr s and turning them to rentals.. you could have a supply demand issue as well.great pictures are a must though in all marketing.. instant communications for a large outfit may be unrealistic.. 

The way I got started is I went out and found a deal that had high value-add(Large margin between acquisition and repair cost and ARV), the value in the deal made it easy to finance, I mentioned to everyone I knew what I was doing and let them know I have a deal I am trying to find a partner for and I found an investor rather easily because of the value in the deal, the deal attracts funding, get yourself a deal and  you will find an investor.