We would not recommend mounting the same home directory onto multiple servers. Even if you are able to customize the location of
.rstudio, you will have problems when people are working on projects at the same time.
I'm going to guess that you are doing this in order to share code and data. Instead of mounting the same home directory for everyone, you should let everyone have separate home directories, and mount your code and data to a separate directory. If you want to encourage people to use this separate directory for their R sessions and projects, you can use RStudio server options to set the default directory for new projects and new R sessions.