I am so sorry. And yes, a whole shaped like Rory will stay in your heart. The only good thing is that as you love more, the percentage taken up by that whole decreases as your heart grows bigger.
Like your "one man gang, furry wreaking ball, Tim the tornado, clown, and wild man" Arwen missed dog companionship. We lost Sayblee to cancer and she tried hard to make the chow-coyote take her place. Much to the disdain of the Chow who let her lay next to her with a look of both horror and disgust. The we lost her to cancer and we knew our aging Rottie would not be long behind her. So we got Cara. I had to have a young dog because of Arwen's termperament and while a male would have been a safer bet, I wanted another female.
You might consider what he gets along with, his health and energy. If YOU want another long term commitment, getting a puppy and making sure the humans take the brunt of the exercise/play so it doesn't bother/stress Tim. Breeders have upcoming litters and I believe BRAT has 5 young puppies you could apply for.
If you are comfortable with an older dog with more similar energy levels, either rescue or breeders may have dogs ranging from 2 yrs up that need a home.
But the decision for a new dog needs to be based on the humans more than Tim. Tim may only be here a few more yrs, but unless you get a senior dog, you got a long run ahead. So the answer is, it is time to get another dog when YOU are ready. You can comfort Tim by lavishing more attention, walks, training, play and even grooming time. He'll adjust til/when you are ready.