I bought an X-Keys programmable keyboard and had to make shortcuts for all of the commands I wanted to make into key selections. This really helped. 
Interestingly, I have a plugin called "options.rb" which has two plugins on its toolbar called "center selected" and "zoom selection extents". They both work fine, but when I try to find them to create a shortcut I cannot find either of them!!
If an object is selected it will zoom to that object: if no object is selected it will zoom to the model extents just like the SU version (Camera/Zoom Extents).
To make matters more elusive, both of these plugins exist in C:\Program Files (x86)\SketchUp\SketchUp 2013\Plugins\Toolbars\Files\Sketchup\commands
This is the zoomExtents.rb:
cmd = UI::Command.new("CameraZoom") {
if Sketchup.active_model.selection.length <= 0
Sketchup.send_action "viewZoomExtents:"
else
Sketchup.send_action "selectionZoomExt:"
end
}
cmd.large_icon = "../images/zoomExtents_lg.png"
cmd.small_icon = "../images/zoomExtents_sm.png"
cmd.tooltip = "Zoom Selection/Extents"
cmd.status_bar_text = "Zoom to selection, or model Extents if no selection."
cmd.menu_text = "Zoom Extents"
#cmd.set_validation_proc { tool_validation_proc("CameraZoomWindowTool") }
@cmd = cmd
But the tool tip for the Camera/Zoom Extents doesn't say that. It says, "Zoom the camera in or out to show the extent of the model".

Can anyone tell me how to make the two plugins in the Command file active? (Putting them into the Plugins folder doesn't do it.)