Now I have another set of new o-rings and the Permatex goop is setting up. I applied it to the sensor around the black plastic housing behind the o-rings so when I re-installed it the o-rings got pushed into the opening with the goop behind it effectively trapping the goop between o-rings and exterior housing. I let it sit for an hour at finger tight before torquing the bolts to 10Nm. There is a slight taper on the outside of the opening presumably so the o-rings can slip in easier (I forgot to take a picture) and since the part of the sensor that's inside the case is slightly smaller than the opening the sealant will be thicker there. Instructions call for waiting 24hrs before use so to be on the safe side I'll let it sit for at least 48. This stuff is not really designed for filling gaps and provided I did not create any air holes when installing it and it'll set up properly I hope that this will be it once and for all.
Of course I may never get that sensor off again after this...
At least now I can go back to obsessively tracking my Vandemon exhaust which is apparently just hanging out at the airport right now.