I have never tried it on a "Belly Band" but I would think that it wouldn't work out too well. Dicor is a "self-leveling" sealant, and thus wouldn't stay put when applied to a vertical surface. It is generally used to cover and smooth out larger flat areas, such as an area of the roof in preparation for mounting an A/C unit or vent fan. The width of most trailer belly bands are not very big, so getting enough of it to stay where you need it would be problematic. I'd opt for a Butyl rubber based adhesive with enough "sicking power" to stay where it is applied. Just my 2 cents.