In my experience, I have had a fewer number of people look at units during this time of year, but a higher percentage of applicants are serious as opposed to a higher volume viewing a unit in the warmer months but many may not be as seriously interested.  

Debt divided by income gives them a percentage.

Not sure how it works there but in SC you'll have to put a certain percentage of the purchase price up front cash, 5%-10%.

I see the supply and demand issue as a good bit of them are in rougher neighborhoods and are probably have a higher tenant percentage vs.

You might also consider utilizing percentages and have values based upon the rent, such as the security deposit being equal to the first months rent, this way it can vary from property to property but won't be construed has being different for an arbitrary reason.Disclaimer: The information in this post does not constitute legal advice and does not establish an attorney-client relationship.

Or to require a larger percentage down payment? 

I saw a survey of over a thousand vacation rental owners previously, a small percentage do not provide LinensI am planning soon to offer a budget option where they must pay cash, bring your own Linens, a couple other things and they can get 10% off.

That might scare off the idea of having a higher percentage in the deal depending on how you present it. 

The smaller the loan, the higher the percentage is likely to be as both require the same amount of work.* **Documents preparation fee**: a charge for preparing key documents, including the refinance mortgage, note, and truth-in-lending statements.

Currently, a lot of companies are switching to percentage of current home value for hail damage deductible.