Not a good plan. It does compromise the strength greatly.
I have seen buffers with the wall strengthened with a welded on plate to have a thicker wall to be tapped.
Rule of tumb. For aluminium 1/2bsp needs 14mm of thread. 3/4bsp 20mm and 1"bsp 25mm.

If the couplings are removed and remounted on regular basis, it is better to have a steel or bronze insert.

Easier option is to use the already available threaded hole with an adaptor.