Installing Progressive SurgeGuard

Everyone has a different opinion on where to place the surge guard electrically. Our RV has 50 amp service and our generator is an Onan QD 8000. I plan on installing my Progressive EMS guard downstream of the ATS this spring. I'm less concerned about my generator than shore power. This genny is only 120 volts anyway, whereas shore power is split 240 volt. That being said, the ATS switches both primaries and the neutral using mechanical relays. The contacts on these relays can and do go bad over time. If I install the surgeguard upstream of the ATS it will protect the ATS, but if the neutral contacts fail in the ATS while on shore power, I could still have major electrical damage in the RV. With the surgeguard downstream of the ATS, it will protect the RV in the event of this particular type of ATS failure. The ATS is more vunerable with the surgeguard downstream type of setup, but I would rather deal with replacing the ATS than a bunch of appliances and wiring possibly.

My thought process here may be faulty and if it is hopefully someone can point out where, but that is my two cents for 50 amp service like OP mentioned he had.