Best way to fund 500K Rehab

[Matthew K.]

Some Detail....We bought our 2nd airbnb Brrrr. Fantastic value estate my wife worked 2.5 years to get for $500,000, waterfront in Fort Lauderdale. House is a tear down essentially. Couldnt get a mortgage so paid cash. Raised 300K from HELOC on 1st airbnb and another 200K from my investment accounts (have another 1.9M roughly in a ROTH IRA that we are OK to withdraw early and pay taxes and penalities buttt....)

So now we have new architectural/engineering plans for a 3/2 2000sq ft home that will have permit approved likely within 4-6 weeks. A New dock/seawall (permit pending), new pool (permit pending), new driveway and new landscaping. House budget is roughly $415,000 (roughly $205/sq ft rehab/rebuild). Exterior budget roughly $125K and we are ok paying with cash for this portion. 

My question is we have $500K cash in the house, but it seems a HELOC on that house is unlikely because an appraisal is needed and appraiser may note that house is not liveable (cant really tell as exterior is fine, but never know). I got quotes from RENOFI for like 9% plus 1 point and a Renoloan from a national bank for like 7.5% (3 weeks ago so prob roughly 8% today.) This loan seems similar to a construction loan as they work with GC on the draw (but we cant get a construction loan because its not "new construction" (leaving exterior walls and foundation).

What would you do? I'd perfer to have all $415K budget for house via debt but also would like to mortgage the property upon completion to get the cash out 80% LTV. The ARV will be between 1.8M-2.3M depending on factors. We will be in roughly 1.05M. (It is likely an excellent deal in a tough market but wife spent years working on getting it thru estate.) Likely take ALL cash out of deal ASAP. We closed in July so dont know what the seasoning period would be to get our money out (id hate to have to wait 12 months after we close) because we will have so much cash tied up in the deal.

Thanks for the technical advice. Couple questions in there and open to working/discussing this with lenders in BP community who understand this unique situation. 

Matt