No one in our area has adopted this trick at all (our ADU liberalization being brand new). 

Not to argue, just sharing my perspective: brand new wholesaler doesn't need to close 10 deals/mo.

Would it be under the business tax id number which would be brand new (so no history yet) or would it be through me personally through my own credit report/history?

Up until now I had given him the benefit of the doubt that he was just busy with his other ventures and that surely someone who had worked so hard to build his brand would not tarnish it by treating his JV investors poorly. 

Brand new to this forum

Further, there are a wide spectrum of lenders that can range from very good to very bad among lenders that brand themselves as "Private Money" "Hard Money" or "Private Lenders"Your best bet is likely to follow reviews and like you've been doing now with partnerships that you trust, but your instinct is right to have relationships with multiple lenders and options. 

after about $550,000 in remodel costs we reopened the wash under a new name with new logos and branding. we introduced targeted online marketing ads, negotiated wholesale pricing deals with local car dealerships to offer a year of free carwashes with the purchase of a new vehicle. created a monthly newsletter and sourced emails from local businesses. all in all I would say we double or tripled the bottom line numbers of the business in six months and boosted google reviews thru the roof!

It has granite countertops, brand new appliances, new kitchens and bathrooms, etc.

Here's what's she says, "It will be brand new when you're done with it.

But, you can build something for 150k and sell it for 300k brand new all day.