Nothing structural, but more than just aesthetic changes.

A good property manager will be able to help you with this as they should have a good pulse on the market for the aesthetic demand of things.Also, you can ask your contractor if they have someone or work with someone who aids them with design of things.

We will be doing some aesthetic improvements before renting, and furnishing one of the units for midterm rentals. 

So to be a bit more clear, we are not looking for more land to "build" on, we are looking for an aesthetically pleasing atmosphere for our permanent and temporary RV tenants.

An architect is perfectly suited for this With knowledge of construction processes and sequencing, aesthetic sensibility, construction contacts, project management, and budgeting skills.  

Should I bother increasing the aesthetic value (landscaping, newer homes, etc) to make it feel/look more like a Mobile Home Community?

Mostly owner occupant neighborhoods (for both aesthetics and resale)  ( to that point in SFH sometimes rental units are obvious, however with the condo taking care of exterior maintenance, it mutes the negative effect of poorly maintained rental units.)

I'm sure if the aesthetic design demand changed, they would change with it.

I am repositioning an 8- Unit Apartment  (Photos Here )  In my analysis i knew that the property was being under rented & with capital & aesthetic improvements i could drastically raise the rents.  

I will do shingles if steel does not look  right aesthetically.