FHA does not allow you to do things outside of the home like adding a fence, hard scaping, retaining walls...   

Glazing in walls, enclosures or fences containing or facing hot tubs, spas, whirlpools, saunas, steam rooms, bathtubs, showers and indoor or outdoor swimming pools where the bottom exposed edge of the glazing is less than 60 inches (1524 mm) measured vertically above any standing or walking surface shall be considered to be a hazardous location.

Electric: is the easiest to split, but may require holes cut in walls to separate the units.Gas: gas lines aren't as flexible as wires, but it can usually be done affordably.Water: most cities will NOT install additional water meters on a property.

This has pluses and minuses.If your property is bulletproof such as no framing - cinder block construction, cement floors, gloss white paint slapped on the walls and a cheap window mount AC, then you are in a prime position to make money with S8. 

I am an aspiring serial house hacker based in southern New Hampshire actively searching for my second small multifamily deal in the Nashua area, but I've hit a wall with inventory being so tight in my local market.

Improvements that DON’T drive the ARV as much: Windows, Landscaping, Driveway, Rough Plumbing & ElectricalI agree with @Jaron Walling about meeting the appraiser at the property and providing documentation.

It all depends on the walls you are hitting.

Walls are priced one way, ceilings another, then you have baseboard, trim and doors. 

But if you do have a house that sits in expansive soils and are susceptible to shrinking and expanding they can put pressure on the basement walls (exacerbated by frost/thaw cycles) and cause them to crack horizontally.

@Jaron Walling I bought the property for 67K.