I'm considering installing a mini split heat pump system in one of my rentals currently.

Usually when that happens, they just installed a plug so the RV can hook up.  

You would, however, want to include coverage for building materials such as tile, which would be lying around during the construction process.

The types of improvements that borrowers may make using Section 203(k) financing include: structural alterations and reconstruction modernization and improvements to the home's functionelimination of health and safety hazardschanges that improve appearance and eliminate obsolescencereconditioning or replacing plumbing; installing a well and/or septic systemadding or replacing roofing, gutters, and downspoutsadding or replacing floors and/or floor treatmentsmajor landscape work and site improvementsenhancing accessibility for a disabled personmaking energy conservation improvementsHUD requires that properties financed under this program meet certain basic energy efficiency and structural standards.For more information visit: HUD PortalHope this helps!

For my just renovated triplex which is in a sketchy but quickly transforming neighborhood I'm installing privacy fence to create 3 privacy spaces, 2 of them using the backyard, and  one of them using the side yard.

The larger residential unit just needs a carpet clean, possibly a quick paint, possibly some new windows (would improve the look of the front of the building) and a new tile shower surround.

A common one is vinyl plank flooring since it's waterproof, comes with an extended warranty, lasts longer than carpet, and needs less upkeep than ceramic tile.

If you can afford to put the metal roof on, i would suggest that, in the long run it will save you money ( buy and hold ) it's a good selling point for a flip, but not as important for you to install metal on it.

Triplexes for example.. need stand alone fire monitoring system (e.g. panel) and some of the newer builds, etc will require sprinkler systems to be installed, shared walls between units must all be fire rated (including all doors), emergency lighting required w/exit signs in hallways, etc etc.  

Too many variables to simply say "tile labor is $3-$3.25 per sq. ft."