You're financed at 100% and would be in big trouble if (when) ANYTHING went wrong....would the property even cash flow enough to service all of that debt? 

Ultimately responsibly using leverage (both equity and debt), implementing systems and buying good assets with realizable equity  is how you scale while operating a sustainable real estate business.

This could also hurt my debt ratios if I go to borrow on another investment somewhere like my plans for the STR.  

Signing the lease demonstrates they agree to the terms and then you can hold them accountable.If you don't do this, then the person named on the lease and paying the rent could disappear and you would have no legal authority to charge the remaining three for unpaid rent.

We already paid them a pretty sizeable entry fee ($30k) to cover some of their equity and debt in another project.

If you do have enough other income then you dont even need to lease out this property to start your refinance.However if you dont have enough income to qualify with no rental income offset then yes you will need to obtain your lease(s) and security deposit + 1st months rents deposited before you can utilize 75% of this gross income - your monthly PITIA payment (in terms of qualification on this property refinance.So all in all Id make sure what your current debt to income position is first of all (DTI) and then strategize to see if you even need the leases at all.

Never invest in Longterm assets with short term debt.  

CoghillWe’ve used AppFolio for many years to manage a large portfolio, and while onboarding can be thorough, it’s primarily to ensure compliance with financial and legal standards.

Or for the high-end primary homeowner has no legal way to 1031 exchange; so the deferred sales trust is a no brainer.

Any legal issues I should be aware of in this situation?