Hi, i have 10 acres of industrial land and going to be building out muti use type of storage kind of little bit of everything, rv /boat storage / semi truck parking , and little bit of container storage   and small spaces (5k-10k sqft)  for contractor yards as well .    

Unfortunately I think this may have some ramifications that further reduce the desire for people to get into the trades in the first place (the exact opposite direction we need to be heading).

Remember that if you put your name and doing the flip something happens, you are directly liable to whatever happen.Make sure to protect yourself and your partner in such situations.

Mine at the moment is at 8.5% so I haven't really touched it in a while since I don't want to take a risk for such a small gain.

Sounds like you are headed in the right direction.

For those who don't know ....SDIRA : Self Directed Individual Account. 

Is it that you want direct control?

That should point you in the right direction.

I am a small-time (4 LTR rentals) landlord in Maine.

It really depends on your situation and you probably have low or small transfer taxes not sure of your exact location.In PA just transfer taxes alone depending on your valuations may deter some owners.