A number of things seem like memory loss. 

Having models is great if you understand their limitations.

From 2nd Mortgages to 1st MortgagesWhen I started, PPR was buying primarily 2nd mortgages. 2nd mortgages is essentially loss mitigation (helping the borrower get back on track and stay in their home).

Cut your losses the first time they miss a payment and start the eviction process.

Most look at a Certificate of Insurance and confirm coverage limits but best practices are to (1) become added as additional insured under contractors policy and (2) understand coverage exclusions which are not going to be detailed on an insurance certificate.

@Mike ReynoldsRegarding your comment that if you need funds you can use money from your side business:You can't use non-retirement funds to pay for expenses related to real estate held inside you Solo 401k.Subject to the contribution rules and income limitations, you may be able to contribute non-retirement funds to your Solo 401k (e.g. as an employee or employer contribution) and then you could use the funds in your 401k to pay for expenses related to real estate owned by your Solo 401k.

Just ensure to complete necessary due diligence - this can include, but is not limited to, title search, property inspection, appraisal and/or survey. 

Per our zoning attorney "all that matters is your rights and limitations under the current zoning".

Is there a limit to how high I can go? 

The only way I see a low or no-money-down scenario being viable is if you have a lender willing to lend based on the Loan-to-Value (LTV) ratio, and if you can find a deal where your total costs are low enough to keep the LTV within the lender’s limits.