Power Conditioner vs Surge Protector?

To the OP - you're making this a lot more difficult than it needs to be. As others have pointed out there's nothing you'd be willing to pay for that would be any guarantee of protection from a nearby lighting strike ... the only practical solution when you expect that may happen is to unplug from the campsite power source. As I recommended in your other thread, just cut to the chase and invest in a Progressive Industires EMS-PT30C and be done with it. Sure, it may not be "perfect", may not protect your trailer 100% from "everything", but it's a darned sight better than doing nothing. If you're not in any particular hurry keep an eye on the Progressive website as the company from time to time does offer fairly decent sale prices on these products. As I recall the last sale was a "Superbowl Special", can't say when they might next do this, but sale prices are offered from time to time each year.