I'm sorry you're having to go through this, puppypwr.
These decisions are always heartwrenching.
You have to look at quality of life, not just quantity. Sometimes it just comes down to making your buddy as comfortable as possible. It just doesn't feel fair, though... :sad:
We also had a dog with nasal cancer. She was an indomitable springer spaniel--a lovable, feisty girl.
There was a vague mass spotted on an xray in a spot inconvenient for removal or even biopsy, so we never did get a definite diagnosis. Gradually, the nose bleeds got more frequent and Priscilla eventually succumbed quickly to a massive bleed out when the tumor evidently burst.
...it sounds so grim.
But the good news is that it didn't seem to cause her pain. She passed very peacefully--on her own terms, under her favorite bushes, while we were waiting for the vet to make the house call to have her put to sleep. Because we had been told that she wouldn't bleed out through the nose, it was traumatic for us--but for Priscilla, it seemed quite easy and painless.
Whatever you decide to do for treatment, loving up Yukon is always the best option. Enjoy your time together and build sweet memories. May you have many happy months left together!