Thank you for contacting Ask an Advisor!
I have a couple ideas that may be of assistance. It may not be a perfect match, but check out the communications chapters within the toolbox: https://ctb.ku.edu/en/table-of-contents/participation/promoting-interest.
Additionally, you may consider looking into some of the local zoning ordinances around fencing. It may be the responsibility of the developer to build new fencing/walls for a new construction (which is what this sounds like).
It sounds to me that your first step may be to identify the individual(s) who have the authority on the adjacent property. Is it the site manager? Is it the developer? I would begin by identifying and reaching out that person. I personally find in-person conversations to be the most powerful. I would discuss the issue with that person with the hopes of identifying a mutually beneficial solution. It could be the case that a wall is something they also want.
Alternatively, it sounds like you may have some competing interests in the local area. Public perceptions of communities such as that which you describe tend to be fairly negative. Generally, there are coalitions or organizations that are dedicated to working with community members around some of these issues. For example, in my hometown of Seattle, WA, we have the Low-Income Housing Alliance. You may have something similar that you can take your issue to who may have a good idea about local actions you can take.
I hope this information is helpful!