Make sure it is Certified,  Send it to their last known address, with a return receipt if it comes back to you, you MUST keep it for legal purposes. 

I'm looking for info on how much it would cost to have this properly addressed by a professional.

@Jo Ballagh  You have an interesting situation that is probably not specifically addressed in the law. 

However a mortgage or deed of trust is a very different matter.

Addressing the problems is like trying to put out small individual fires in a forest that is burning.

The only concession I got from him was (1) He and all crew members will sign a hold harmless release of waiver of liability form in case any of them got injured, and (2) cash means I will write him a check in his personal name.So I do have cancelled checks to individual names, even on the check I wrote a reference "debris clean up @ address". 

Costs associated with them and trust factors?

That is correct, anything that is not on the contract as an exception if you purchase title will be addressed."

What are you doing/saying to gain the trust of your potential clients?

Most Hard Money Lenders have a minimum of $50k.Here are two good resources to find lenders:https://www.scotsmanguide.com/Residential/LenderSe...https://privatelenderlink.com/You can bring in a private money lender to provide the $25k secured by 1st Trust Deed.Where is the property located ?