Something that comes to mind in the latter case, there could be rental restrictions as part of an HOA. 

You would just need to be diligent in asking whether each property has subleasing restrictions and what are their requirements. you will find that some condos/co-op require you to live for a minimum of 2 years before you can sublease; or some may not allow you to sublease at all; or some may have a limit for the time frame in which you can sublease. it all depends. 

There will be DTI  and down payment restrictions  due to overlays of lenders on lower credit score. 

The ideal market is one that has restrictions on housing stock growth, combined with market growth. 

Often, voucher recipients have income restrictions placed upon them, so it might be almost impossible to locate a S8 applicant who has a voucher for $1K and a w2 income of $2K. 

(You can read more about the full requirements/details here: https://barneswalker.com/seller-financing-restrictions-under-the-dodd-frank-act/.)There are some other things to think about though. 

I’m hoping all financial impact is restricted to the LLC itself.

Purchase: For a purchase money transaction, the LTV is determined by dividing the loan amount by the lesser of the "as completed" appraised value of the property or the sum of the purchase price of the property and the total rehabilitation costs.Refinance Transactions: For a refinance transaction, the LTV is determined by dividing the original loan amount by the "as completed" appraised value of the property.Eligible Renovation: There are no required improvements or restrictions on the types of repairs allowed.

So here is the actual verbiage from Fannie Mae:Second Home Requirementsmust be occupied by the borrower for some portion of the yearis restricted to one-unit dwellingsmust be suitable for year-round occupancythe borrower must have exclusive control over the propertymust not be rental property or a timeshare arrangementcannot be subject to any agreements that give a management firm control over the occupancy of the1.

There's going to be some restrictions to this though.