The existing infrastructure includes an RV park with 16 hook-ups, complemented by an impressive 81,000 square feet of diverse buildings, featuring a state-of-the-art 54,000 square foot indoor arena, a 26-stall indoor horse stable, a 40-stall covered barn, public restrooms, and a 3,500 square foot, 20-foot ceiling insulated metal building.

It can get dusty, or if prospective tenants use the restroom, however it is not standard practice at least in my area to have monthly cleaning for rentals, however some of the bigger sales companies do monthly cleaning so they could be taking their cues from there.

The issue is state wide ADU rules to not apply to duplexes (it applies to SFR) and I do not believe LA allows the ADU be added to duplexes.I think you would have a hard time getting R2 to get rezoned R3.If you can get the rec room designation I suspect you can leave a kitchenette and restroom. 

As the land lord, you might also need to consider dump stations for grease and what not, clean restrooms/portapots, sitting area and someone to keep trash picked up.

They usually have warm air blowers built in to dry If they work as poorly as the hand dryers in public restrooms, you'd have to sit there a looooong time to get dry! 

Did you build and office and public restroom on site for residents to use?

The sweet spot for me on the smaller shops are 2,000 sqft, with 1 restroom and 2 offices and the rest in warehouse space.

You will need some lighting , portable restrooms , water would be nice , gravel for parking areas , tables .

Zoning and use is obviously the first biggest concern, second is demand, they dont want to sign long leases, maybe month to month.Power and restrooms.

My immediate plans is to rent the home and the mother-in-law suite once I'm complete with the cosmetics and the addition of restroom and kitchen.