Your best option for the remainder of the renovation costs may be credit cards (assuming you're comfortable with that), and of course friends / family / partner, 401k loan, etc.   

We're cash poor at the moment and don't have the money to buy it right now.All together, we own roughly $4M in properties outright.

Brick itself is a poor insulator. 

Talking with a few local credit unions but wanted to see what some national banks would offer.

You then report the income in CDA and a credit for US taxes paid.

You are basically taking out a loan for personal use, just as you would spend money out of the credit card to buy a food. 

Fortunately, I have excellent credit, but I’ve been an independent contractor for the past 6 years, so I worry about qualifying for a mortgage.

You can’t even offer rent credits or require the tenant buyer to do maintenance on their property anymore

He's telling you to wait a week because you're going to go look at cars in person, or put your contact info on some website, to "think about it" a week earlier than whatever he tells you (this is 100% true, and as a lender I will not believe you if you tell me otherwise... sorry :P ), and the second you walk onto that car lot a bunch of car salesmen are going to descend upon you, deploying various lines of BS as a pretext to run your credit ("it's a soft pull" or "we just need your SSN to verify you aren't a terrorist, we aren't going to run your credit") and close you on a car that very day, and there is greater than a 0% chance you will believe what they tell you and screw everything up.The rule is that whatever you tell homebuyers not to do, some non-trivial percentage of them are going to push it one notch farther than you tell them.

Then you can pursue in small claims court or put a deficiency on their credit report