Not sure how you can resolve the issue of over/under salting to accurately forecast cost, but you may want to consider having them use a calcium-magnesium-acetate snow melt in lieu of traditional rock salt.

Which would most likely lower your monthly payment if it’s interest only payments ( which would be your best option to keep your DTI low to  qualify for a traditional loan).  

When looking to help someone acquire their first deal, I often show them some of the new construction options because the repairs/maintenance should be light the first 5 years.

Traditional financing.How did you add value to the deal?

Traditional conventional financing.

This especially holds true if someone is not a traditional home buyer or seller but looking to buy an income property as an investment.

I know more about traditional lending (since it's all that I have used at this point), so pardon my ignorance. 

Overall, we had to put on a new roof, extensive landscaping, "60 years of growth never cut", new decking, new fencing, completely remodeled kitchen, updated fixtures and lighting, paint, electrical upgrades, and drywall repairs. 

Often people use a combination of buying with hard or private money, renovate the property to build equity and then refinance with a traditional loan to get all or most of their money back.

The forced appreciation play in small-plex's has a few key points that the traditional SFH BRRRR does not.