Hello Gents, one option that hasn't been mentioned yet is silicone adhesive. I have used your common clear general purpose gutter/downpipe/wet area silicone adhesive on multiple jets with complete success and 100% reliability. Points to note:

-ensure all surfaces are clean prior to gluing (use a degreaser that is no too harsh as some paint finished can be affected)
-only apply a few small "dabs" of adhesive as it is heavy and if left to cure for a few days is very strong (so only small amount needed)
-tanks can easily be removed but cutting the adhesive with either a knife or thin wire, etc.
-almost all traces of silicone can be removed if needed with a knife and rubbing action


If you are using quality tanks and hardware, the tanks will only need to be removed for maintenance - which will not be too often. Some tanks, depending on their location, can be serviced left in place, etc

This method is not suited for tanks that require frequent removal to service other aircraft items, etc

BRG, Frank