The lease doesn’t state anything about him having a front or back yard, it says the communal patio and garden space needs to be kept clean.

Clear the patios and hallways.I would also like to know about the people staying in my house, just like when you find tenants yourself.

The total footprint will cover garage, laundry, and include small outdoor patio.

The renovation consisted of all new interior and exterior paint, removal of popcorn ceiling, complete floor removal and install, complete kitchen remodel which included a wall removal and converting half of a closet into a pantry, complete master bath remodel, 2/3 remodel on guest bath, All new interior doors and hardware, new front door and hardware, new lighting fixtures, new landscaping, new paint for patio and front sidewalk, and pressure washed driveway.

Would it be worth it to simply have a crew come in and make the entire back yard into a small brick patio?

The patio is probably graded away from the house, so it diverts the water away from the wall.  

Bandit signs don't have to be the corrugated plastic ones stuck on telephone poles.

Charlotte Landscape and Patio is good. 

These people know that most diseases that are transmitted readily through surface contact have more trouble with glazed ceramic surfaces than they do with plastic surfaces.

Not sure if the manufacturer can help, but they might have some insight.Vinyl, and plastics in general, just aren't very reactive.