While not water damage, my Trail-lite had some disbonded spots on the outside walls. I drilled several small holes in the void and injected 9309 Hysol resin then placed a rubber vac mat on it and placed it under vaccum for a few hours to keep it flat. That was three years ago, and it has not disbonded again. It still looked fine before I left for Iraq. I repair aircraft for a living, and that is how we fix voided honeycomb structures.
1994 International 4700 powered by a DT360 (5 years and still working on it)
1990 Ford Bronco II