The secret to getting a good seal is to apply the sealant, install the bracket but don't tighten the bolts to max yet. Wait a while for the sealant to start to set and then tighten the mounting bolts to spec. Using that approach makes is less likely that you might squeeze out all of the sealant in spots. You will have to experiment a bit to determine how long to wait. That depends on the product, the temp and humidity. Note that the sealant under the two parts will cure slower than the material that oozes out.