Sorry didn't see Schoonerlabs and Pauls posts
Yes the Seacon bulkhead connector would install in the BR end cap penetrator hole with out any issues that I can see, The plug end Min-CCP would have the BR tether inserted into it and connections made inside the plug. This would not require an inline splice like using a pig tail type connector. You would have to make sure you get the correct end for the diameter (gland) of the BR tether
At this time I am not using a BR tether but a AV cable mated to floating rope, this is a fragile set up but have used my old one for 3+ years and am now re-building my ROV with a BR 4" Acrylic hull so building a new tether
What didn't work on the other style you tried? What method did you use to mate the BR tether to the pigtail (solder, crimp? layers of shrink ect)
I just made my new tether with that type of pigtail plug and was not happy at all with the my splice even on the third try. So the reason with going to try the bulkhead connector and matching plug. I used a similar set up on my present hull and was happy with it.