Try someone else, have them quote it and go with the cheaper quote.
Extras are going to be proportionally more in a Tesla system because the system itself is so cheap. Your cost doesn't seem super unreasonable depending on the layout, maybe a couple hundred high. Typically it needs to happen on all 4 sides, as the skirts wont prevent small critters from entering. Its not just chicken wire, but similar. How many feet of perimeter screening do they have to do?
Tesla doesn't really want to do your extras. If you ask them to do it, they will charge more.