So, you're actually making the argument *against* debt (not for it).I think you mis-understand debt, risk and the alternatives.

Bigger Pockets sent out an alternative investment article which included ATM investments as a suggestion. 

Alternatively, explore a self-directed IRA to invest directly in real estate without triggering taxes or penalties.

Best case under such circumstance is they find alternative financing and simply over paid for the property.good luck

Promissory notes in general, as they have no collateral, seem a bit higher risk, perhaps mortgage note investing which are backed by residential and sometimes even commercial real estate would be a safer alternative, and yet very lucrative, too,  8-12% yieldsFor extra returns, I put a small portion of my portfolio into BDCs, Business development companies, that specialize in loaning money to growing businesses which are too high risk to get loans from proper banks.

., etc. for example finding cash flowing investment properties which meet your ROI goal of 9% is NOT HARD heck almost every state (and likely every state) has a market which will achieve that but what does 9% mean without a dollar value if 9% is = to $200 or more okay that’s okay but if 9% means $25/mo. or alternatively if 50% ROI means $25/mo. doesn’t really matter much since although labor differs from area to area it doesn’t differ that much and also doesn’t really leave much room for error — so your minimum accepted ROI should also be couple within a minimum accepted $$ value (cash flow) and other minimums as well (i.e. min. equity, property types, property classes, etc.)Lastly as I mentioned achieving a 9% ROI is not hard and is achievable in every state; the HARDER part is to 1) achieve that AND 2) achieve 10-20% min.equity on the buy in or ARV AND 3) meeting your min. $ value AND 4) buying in a good/stable neighborhood/market AND 5) buying with some type of upside AND 6) etc. etc. etc. —- Again I’m not saying you have to do these things; it all depends what type of investor you are and what you are looking for however it is important to understand that if you shift the responsibility of either identifying the invest property or managing or any other aspect there WILL be a trade off — in this case the turnkey company has delivered on your goal of 8-9% ROI (projected... so TBC) and in return you have traded some of the other benefits of investing in RE for the convenience of not having to do much more than to look over the properties they have sent you and funding it from the comfort of your home, office, etc. ... again if this is the goal then you are on point but if the goal is to also partake in ALL of the other benefits of RE then you should understand that and not be surprised that it’s not a ‘stellar’ investment that checks all the boxes.

I am wondering if taking such a risk would stretch me really thin or is there a safer approach to take.

Sometimes the items are not a deficiency but merely a recommended alternative way to complete something and those can normally be talked away without even making them into the report.

Banks who offer construction financing tend to be 75-80% LTC and alternative/hard money lenders will sometimes offer higher LTC leverage than that.

I would focus on credit, consider some alternative options to "free your Benjamins" out of your home, or even consider doing a partial sale of your home to give you capital to get back at it!