Plus of course, if asked in court what assets you own, short of perjury you would need to disclose you are the beneficiary of that trust which holds the property. 

I would ask if he is willing to disclose leases and expense books before you even offer.

I was told by an insurance friend that once I do that, my vehicle becomes commercial and if I didnt disclose to insurance company and became involved in an accident, there could be some problems paying out a claim, etc.Thoughts?  

As I mentioned, I am an agent so I know I must disclose as much as possible.

Once you know about anything major you must fix it or disclose it to potential buyers. 

You have to maintain your license, and you have to disclose to private parties that you are a real estate agent, especially if you do marketing.  

How much do I disclose to them about the project (BRRRR)?  

You get full access to mls and can run better comps, you get commissions, I've found that disclosing only builds trust and in turn helps build your business, it keeps things out of the grey area no matter what state you're in.

I don't know how litigious Michigan is but here in the great state of California it gets rather ugly even between "good friends/co-workers", so I would definitely make sure everything is disclosed and done correctly but that is up to you.

As a source of personal reputation and guarantee of good quality, would I be able to share photos of the builder's past projects without disclosing the builder's name or something like that?