Rstudio Connect allows for several versions of R to be installed simultaneously. (You don't have to switch entirely. You can keep 3.4.2/3.4.4 etc... available for whomever needs them)
Admin Guide on installing R versions
https://docs.rstudio.com/connect/admin/r.html#r-versions
In line with the above, every so often I add new supported versions of R at /opt/R/
First I get the source of both 3.5.2 and 3.4.2 and drop them in /opt/R/src/ (make the directory if it is not already present)
wget https://cran.r-project.org/src/base/R-3/R-3.4.2.tar.gz /opt/R/src/
wget https://cran.r-project.org/src/base/R-3/R-3.5.2.tar.gz /opt/R/src/
(I get both because, I do not want to rely on the versions installed with the package manager, since there's a risk of an update making those go away)
untar those files and then compile them. It so happens that Rstudio has a guide for compiling in Centos:
https://docs.rstudio.com/connect/admin/getting-started.html#installation
When this is done, Rstudio connect will scan automatically and find these.
(Note if you rely on your Rprofile.site, which I do, you will need to make sure that you edit the files in their new locations)
Example
/opt/R/3.5.2/lib64/R/etc/Rprofile.site rather than/usr/lib64/R/etc/Rprofile.site