Ignorance IS a defense in residential, and one a party can file a class action lawsuit on because that's much of what just happened nationally.

Could you advise where investors typically secure financing for similar land purchases?

If you think you might get kicked out then housing security might be worth upping the payment. 

Permitting also secures compliance and avoids fines, which can be significant in LA.This post does not create a CPA-Client relationship.

If they don't you personal financial situation plays a bigger part in securing a loan. 

There is also the lending field which is quite lucrative if your more into financecommercial real estate if some day you want to be doing bigger deals and making 6 figure commissions checks.. etc etc.to try to start your business as a flipper or wholesaler is tough and it has a 95% failure rate being that it appeals to the mass's of which many frankly don't have the skills to succeed or the financing behind them.OR converselyMake money at your chosen profession save and buy and hold.. buy the best you can hold for long term.. same with buying securities .

Or even missing out on securing a better deal, higher price, or greater return but did not do so, often due to a lack of negotiation or oversight.

He collected first/last/security payments prior to move in date and was never heard from again.

My strategy has been to grow aggressively (by using as little of my own money as possible) to secure good assets, and once stabilized, then work to pay down loans to own them free and clear sooner rather than later. 

And, they generally bring forth action when a neighbor files a complaint and the fines/remedies can be painful.