Hey @jdblischak, one solution I use a lot is rmote. It doesn't forward plots to the RStudio plot pane, but it does forward them to a server that you can access in a web browser. Basically, you install the package, SSH in with the port the server will listen on forwarded (which you specify in the SSH command) and then run the server in the remote R session (which you can do in your remote .Rprofile if you like). Then you just leave a browser open on localhost:XXXX (your forwarded port) and plots (ggplot, lattice or base), htmlwidgets and documentation pages open in the browser. You can choose which types of things go through it, and there's a nice history pane in there too.
It's not quite a native RStudio experience done remotely, but it beats the hell out of an X11 window 
It's also particularly nice because the servers I use are organisational—I can't install RStudio Server on them, but I can install R packages