Max, it did take a bit of work, but with the limited resources available it was by far the best approach. And it did not take that much effort to cut the housing. In a few months I am going to need to do even more: Add a 4by4 junction box to a conduit run without cutting the cables that pass through, or pulling them out to do the work. Each of the cables is reclaimed computer cable, 2 shielded pairs of #24 wire, all in 3/4 inch thinwall conduit. The j-box has to be added because of additional microphones being added to the system, to go with the new 16 channel sound board.

 

did not notice this topic before but... you just need to choose one of the 'cable entry systems' or 'split cable glands'. many forms exist for this very use. just ask your nearby electrical supplier (not electronics supplier).

the rubber blocks are cut on one side allowing cables with connectors to be inserted sideways.
then when assembly is clamped it usually forms IP67 seal. extra holes can be plugged by supplied solid blocks or dowel pins.

 

 

https://www.icotek.com/en/products/cable-glands/qvt