Replacing my belly pan and drilled through my black water tank
If a decent epoxy is applied to clean, dry, freshly cut threads it will stick and damn good,
A person could add some insurance by scuffing the area where the screw or bolt head will contact the bottom of the tank just to be sure if there are any doubts. (I would scuff it aggressively)
Epoxy WILL form a mechanical bond to abs to the effect of sealing the threads of a screw against a gravity leak no problem.
The fact that I am opinionated does not presuppose that I am wrong......