They would cash his checks (even huge ones like $20k) for a small fee, and he would take the cash and pay his guys.

With IoT monitoring everything I could have theoretically been charged a late check out fee.

Below are some actionable steps I plan to take after identifying a market:- find a rock star agent by referral and/or calling brokerages and asking to connect with their top producing agents- find a rock star contractor by referral and/or yelp- have control over construction by setting per diems to incentivize contractor to finish the project on time, within budget, and with good quality- leverage my rock star agent's time to check up on the construction process (checks and balances)- hire independent handymen/inspectors to check up on the construction process for a flat fee (checks and balances) There's competition everywhere, you won't escape that in any market. 

But that wasn’t what the funds were for, they were origination fees - not prepayment for his time to go find a lender.

the fee-based services seem worthwhile at least while actively looking.   

Your management fee is way too low, especially if you're doing everything for the owner.

Can I charge them fees & rent for storage of their crap? 

Additionally, a lender deposit ranging from $20,000 to $100,000 is necessary, along with a rate lock-in fee that typically amounts to 2% of the loan amountIn the process of raising equity, it's crucial to be diligent while filling out necessary forms and securing required verifications.

Qualified renters can opt to pay a non-refundable monthly fee instead of a traditional deposit.

Worst case, those will probably cost you 15-20% in interest and fees.