I live in Southern California and want to start investing in property and grow that, I only have $30k-$40k what are my best options?

One of the requirements is to have a trustee. selecting a friend/family isn’t an option for me.

Good tenants typically take care of the property and stay longer. 

What would be some of the lowest cash options to finance the land/new build as soon as possible?

What is preferable option - should I ask them to be the applicant or should their son be the applicant and parent be the cosigner?

So my question is: Could anything change with the mortgage if the LLC is under new ownership (other than a bank potentially calling the loan due which is typically in any 30 year fixed) Then the icing on the cake: Obviously I'm attempting to pull this off right now lol.

Quote from @Jazzous Anderson: If you can afford it, separating the utilities and making tenants 100% responsible is the best option.

Thanks for all the great advice.Due to a growing family house hacking is not an ideal option for me.

For most people DIY is NOT a good option and will probably fail at anything you are trying to accomplish.This is not legal advice, it's practical advice.

Cash offers with low to no contingencies are typically going to be more appealing to sellers since there are less "hoops" to jump through compared to traditional financing.