Bottom line is that any Trad Catholic who holds that non-Catholics can be saved (regardless of the question regarding BoD proper) is a schismatic, since the entire Vatican II theological system, the ecclesiology, the subjectivist soteriology, they are all the logical consequences of such an ecclesiology, and you'll note that this question has nothing to do with BoD, and the only reason it factors in at all is because many EENS-haters constantly use it to deny EENS and hide behind it to justify their rejection of this thrice-defined dogma.
As for your arguments, "transeo" (I will pass over for now).
...but even in a worst-case, it would still be better than being a Dimondite.
Specifically, even as a "schismatic" you would have a better chance of salvation than someone who follows the Dimond brothers.
Of course I'm half joking here -- strictly speaking, you aren't "more likely" to go to Hell for murder vs. sins of the flesh. They will both get the job done. I'm just making a point here.
I hope you're not defending the Dimond brothers just because they happen to agree with you on BoD, EENS, etc.
Don't forget that even a broken clock is right twice a day.