I'd say treat it as any other rental application, if you're unable to find what you need using the information provided by the applicant or the info that you find is undesirable then you may need to deny them.

Here are a dozen things that can destroy you with a mobile home park:1) Paying too much2) Bad market (small metro population and low home prices)3) Bad location in that market (undesirable part of town that nobody wants to live in)4) Bad infrastructure (failing roads, utility lines, etc.)5) Private water and/or sewer6) Master metered electric and/or gas7) Density too high so you can't fit new homes on the lots8) Mostly 1960s and 1970s homes on the lots, as they will end up getting scrapped as people move out over time9) Low lot rents that make the whole business model not worth the effort (like $99 rents in Mississippi)10) Inability to get or retain traditional financing11) Environmentally contaminated12) City or state permit problemsThe bottom line is that -- if you are going to seriously buy a mobile home park -- you need to educate yourself on this niche.As far as finding mobile home park deals, there are basically four methods used:1) On-line (Mobilehomeparkstore or Loopnet)2) Brokers (over 50% of the 200+ parks we own came from brokers)3) Direct mail to park owners4) Cold-calling park owners

Usually a property offered at 3% CBB has a catch: busted properties, functional obsolescence, undesirable locations, or what have you. 

Personally, I think the West End becomes unaffordable, even undesirable, for a lot of first time home buyers and trade-uppers at ~$300k or $200/sf fully rehabbed.  

is it a desirable or undesirable place to live?  

Gerry,As someone stated, you might find a lower down payment, but you'll likely end up giving it right back again (or worse) in the form of higher interest, or some other undesirable terms.

If the higher risk is undesirable then you have to know you will do fewer or no deals

In other words, what are the best ways I can legally use to make the storage unit a profitable add-on rather than an undesirable burden?

I'm simply stating, in a red hot sellers market, the majority of the inventory will be undesirable and it's up to you to educate yourself and cherry pick based on your individual goals.  

In my ad for the rental, I set some guidelines that should help weed out some undesirable tenants.