You are confused with the metering as well. The meters ARE showing you peak levels all the time. I just did a test where I created a sound that was only 10 mS wide and went up to 0 dB in level. It still registers 0 dB on the track meter which means they are showing peaks
now. Level meters do not have to be installed. Although what
pwalpwal is saying is also correct. Plugins can be installed on any number of selected tracks at once.
A good way to go is to monitor rms levels throughout your system by installing the level meter in a few key areas in your project and put it into K System mode. Or use the Level meter normally and you will see both peak and rms. I tend to monitor rms levels with a third party plugin such as the Klanghelm meter or the recent Waves VU meter (which is excellent BTW) If you choose reference level such as K-20 for example then you don't even have to worry about peaks. They will take care of themselves and you will rarely get a clip light. And don't forget too that the clip lights are also still there too.