I'd let insurance handle it. You don't want to get mixed up in flood repairs unless you absolutely have to.
If water entered the cabin either vehicle it should be totaled. Particularly if it's salt water. I would think that water high enough to saturate the underside of the trailer would total it.
Alllllll that being said, I've had success in restoring flood totaled vehicles. Fresh water. One was fully submerged. It's tedious work but if done right can be good as new. The cost of labor, however, would total it (I did it myself).