Replacing ceiling due to moisture at exterior wall?

[Whippedcream]

New to mobile home although I’ve don’t plenty of regular construction. Discovered some moisture in the ceiling and insulation of our 1987 Zimmer single wide at the exterior wall. I know all of this comes after making sure that the leak is fixed; but I was shocked the difference in construction vs a stick built house. After taking out the wet ceiling panel I realized that the ceiling panel runs out over the top of the exterior wall. When pulling out the damage I wanted to check with those more experienced. Is it appropriate to support the truss with an equal thickness piece of plywood after removing and then replacing the insulation that was affected? Anything else I should know would be great. Thanks.