Otherwise, renovate the garage into a man cave, while keeping the garage elements to easily convert back with no or minimal cost in the future.

We have struggled for years deciding whether to sell or hold because the tax implication to sell is very costly.

This is tough.Depends on how fuzzy you want the business/family line to be.The only thing I'd be absolutely sure of is that your money has more tangible security than being a "personal loan" EVEN IF you cut him a break on cost. 

Also, for anyone based in Philly, I've heard from one contractor that quotes of 20-30k were common a few years ago, but due to recent rule changes, contractors need to maintain excavation licenses/ insurances to do any dig out work and that cost is getting passed to customers.

Given the current market conditions my credit situation,and a title cloud that shouldn't be there, I'm exploring various financing strategies to manage this debt effectively.

DSCR is a better option on rates and cost compared to Fannie and Freddie loans.  

That generally means going where housing is still relatively cheap, holding costs such as taxes and insurance are relatively cheap, and there is a lot of upward pressure on the housing market. 

These are some of the ways the clients could be affected by property managers who are not prepared: Extended VacanciesInadequate marketing strategies and tenant screening processes can result in prolonged vacancy periods, translating into substantial lost rental income.High tenant turnover due to poor resident relations further exacerbates vacancy losses.Inadequate Maintenance and RepairsNeglecting preventive maintenance and delaying necessary repairs can lead to accelerated property deterioration and higher long-term repair costs.This can also negatively impact tenant satisfaction, contributing to higher turnover rates.Legal and Compliance IssuesLack of knowledge or disregard for landlord-tenant laws and regulations can expose investors to costly legal disputes and penalties.Failure to properly handle security deposits, evictions, or fair housing practices can result in significant financial liabilities.Ineffective Financial ManagementInaccurate budgeting, expense tracking, and financial reporting can lead to uninformed decision-making and missed opportunities for cost savings.Failure to optimize tax strategies and leverage available deductions can further reduce net returns.Diminished Property ValueInadequate maintenance, high vacancy rates, and poor tenant screening can negatively impact a property’s perceived value and appreciation potential.This can significantly affect the long-term return on investment when it comes time to sell the asset.While a 10% management fee may seem reasonable for a well-performing property manager, the cumulative impact of mismanagement can quickly escalate the effective cost to investors, potentially outweighing any perceived savings on the management fee itself.

After analyzing the deal further, estimating holding costs, realtor fees, monthly costs on hard money, estimating the worst case scenario of it taking three months to sell (average time here is 43 days), rehab costs, insurance, etc., I am pretty sure we need to pull out. 

I love this idea, but would first talk with your ciry to determine the building regs.Have you done any comparison to see the cost difference than just building a typical multi-unit property with small units?