I put mine between a hughes autoformer and the transfer switch. The generator on MY RV had it's own form of protection (If it was over/under voltage it simply shut down) But some folks like it after. Your choice but on my RV the Generator did not have the safety ground so the unit would not pass Genny power without my making other mods I choose not to make.
Most people don't try to protect from flaws in the onboard generator output, since it is rarely a problem and many onboard generators have at least some built-in self diagnostics anyway. Thus they place the Power Monitor between the shore cord and the transfer switch (the easiest place in most rigs). But there is no downside to placing it between transfer switch and the power center, if that is your preference.
You do, however, want to have the 35530 in a place where you can easily view the indicators, in case there is a power problem. That is often the overriding factor in choosing a location.