This is active real estate, even though you are rehabbing a rental, because you are committing your time that is what makes it work.If you decide to work with a Provider that does most of that for you and you simply are the financial backing then you will sacrifice about 10% of your potential profits, but you will gain back security and time. 

What steps have you taken to secure that form of financing? 

I feel something like 1 point origination and 10% interest would be fair. 1st lien position secured with deed of trust, max loan amount of 75% of ARV.

A wise investor might ask some of those folks if they'd rather earn 3% on an investment secured by real estate. 

I’d want to be partners in everything… if you are able to secure financing or some other value, you should be rewarded for that in the deal somehow.

This is where my question comes: How can an 18 year old secure invests for a commercial deal?

Most humans, once our basic needs and security are met, are far better off in life by measuring incremental joy than by measuring incremental financial returns.

Definitely get that legal opinion, not just on the OA but on whether this is offering a security or not.

The seller got really mad over something and kept the security deposit.

@Kevin Kohler was looking mainly for typical residential HeLoC access with the property securing it.