Your thinking is accurate.
It will take some "doing" to intercept rewire the household junction box to add an outlet for your exterior surge protector to be in series with the circuitry, but it will work - providing you have the space.
I have a truck camper and was worried about theft (we're going to Mexico!). So I squeezed the in-line surge protector in side the TC - just barely enough room.
I should mention, as you probably already know, there is about a 140 second delay before the surge protector allows shore power to connect to the camper.
Kind of a pain, that.
