Most mortgages don't allow seconds but honestly, the bank isn't going to check so you could roll the dice on that. 

Thanks for checking out my website!

Check out this article on BP https://www.biggerpockets.com/blog/multifamily-dscr-loans that goes into more detail.

Almost every residential area is zoned for multi-family (I have already checked and verified this) it just so happens that most of the homes on the market are SFH.

BUT you have less red tape, no tax returns, DTI, or employment checks are required.

I can still hold properties under check book SDIRA?  

My questions is: if the LLC collects money for admin costs, such as background check and other membership related costs and/or monthly membership for co-living environment, is it considered a "For Profit" entity or is it a "Non-profit"  entity.  

I would check out Facebook Marketplace, Airbnb, and Furnished Finder to see how much other rentals are going for in your area.Mid-term rentals should be furnished and can rent for more than LTR.

You should also check out petscreening.com.

It is pretty easy for me to price it accurately by checking all the other lake rentals.I do recommend Pricelabs for pricing.