I also have a contracting/remodeling background (mostly custom kitchens & baths) in CT, and am finally delving into the REI space too. 

I think 25k to furnish, stage and stock with essentials (linens, towels, kitchen, etc.)

Should be way less than $40-50k, The Container Stop quotes around that for a 20 footer with a kitchen and bathroom 

Some drywall replacement, repainting, need to add a backsplash to the kitchen, maybe replace cabinets, flooring could be redone.

For example if someone has owned a house for 5 years, but did NOT refinance in 2020/2021, they left thousands of dollars per year on the kitchen table, which most people will not voluntarily do if they have another choice.

According to HUD Fair Market Rental Rates for 2024, the market rent for each unit in the 34608 zip code is $1,700 per month.While the units are in good condition, consider updating the kitchen, bathrooms, and fixtures and adding a fresh coat of paint for a fix-and-flip strategy.

Assuming the portable dishwasher is going in the kitchen....There has to be GFCI nearby since any outlet within 6 feet of a water source in the kitchen must be GFCI or is not compliant with current regulations.

We would like to convert the basement (which is already finished) into a 5th unit, it just needs a shower and a kitchen but that is a project we would get into while living there. 

Everything should be in writing, down to the type and name of the kitchen cabinet handles, the tile name/brand/color, the texture of drywall,....everything that will be a part of this project must be in writing attached to the contract and signed by both parties.

A friend owned self-storage properties in K-ville and he said to me “no kitchens, no baths and no overnight tenants”.