Hiding in plain sight, perhaps?

There are plenty of crew members in the background whose ears and eyebrows are either hidden by hair, or just out of focus. We can fudge some of them into being among the other Vulcans, or part-Vulcan hybrids. Here are a few candidates:

Blonde hair isn't common among full-blooded Vulcans. But if Sela, the human/Romulan hybrid, can be blonde, then surely a Vulcan/Human hybrid can be as well.

Another possible hybrid is Ensign Swinn, from "Resolutions" (Season 3). The writers probably meant her to be Human, but the actress's natural ears make it easy to presume that her character has some Vulcan ancestry.

Then there's this background crewman. Again, this is just how the actor looks in real life (I assume). But in-universe, Vulcan ancestry is highly suspect.

...but why didn't we ever hear about them?

In "The Huanting of Deck Twelve" (Season 6), the computer lists several names while glitching out. Among them are "Ensign Trumari" and "Crewman Unai." Multiple fans have decided that Ensign Trumari is that Maquis Vulcan (or Romulan!) in "Repression." As for Unai, that could be a Vulcan name, or it could be African, Asian, or any number of Earth cultures that could use more representation in "Trek."

Additionally, many aliens on "Star Trek" have names that happen to also be names on Earth. Spock, Lon Suder, (Natima) Lang, Kang, Dax, (Lenara) Kahn... So it's entirely possible that some of the Human-sounding names we hear could actually be non-human crew members, especially if the spelling is never confirmed onscreen. "Macormak" may be an Irish name on Earth, but it could plausibly also be Vulcan. "Ensign Ryson" might really be Ry'sinn.

Then there's the possibility of aliens just having Human names, for whatever reason. Adoption, mixed heritage, parents naming a child after a Human friend, etc.

"Blood Fever" (Season 3)

This episode left many viewers with the impression that Voyager had no female Vulcans, or even that Vorik and Tuvok are the only two Vulcans onboard period. But neither is ever said in the episode. And there are plenty of reasons why Vorik wouldn't just mate with one of the Vulcan women onboard: she's married, she's gay, she's impotent, she's taken a vow of chastity, she's got a telepathic STD, she's just not into him...or, most likely, Vorik is just a picky son of a bitch who won't settle for any less than B'Elanna Torres.

Counterpoint (Season 5)

Oy. This one is the hardest to get around, but I'll try.

"Counterpoint" is a fantastic episode. But if it has one sin, it's the continuity error of stating that Vorik and Tuvok are Voyager's only Vulcans. Still, we might be able to fudge our way around this.

Why didn't Janeway mention the other Vulcans to Kashyk?

Why would she? She likely couldn't hide Tuvok and Vorik's contributions to the mission from Voyager's logs. But if the other Vulcans weren't involved in any major incidents involving their telepathy, then maybe it was easier for Janeway to conceal their existence from the Devore.

For the record, when discussing Voyager's telepaths, there is no mention Kes, Stadi, and the Vulcan nurse from "Caretaker," although Lon Suder does come up. Why Suder was more noticeable to Kashyk than those other three is anyone's guess. The point is, if Kes, Stadi and the nurse--all once members of Voyager's senior staff--never came up in the discussions of telepaths, then there can easily be more lower-decks telepaths who also went unmentioned.

So, where were the other Vulcans in "Counterpoint?"

Maybe they were just off camera. Maybe the other Vulcans were in transport stasis, and re-materialized just out of the audience's line of sight.

Or, maybe they didn't have to hide in stasis, because they could conceal their telepathy from the Devore scans. This could be due to mixed ancestry, or having not used their telepathy in many years, or maybe just some very difficult mental tricks that not all Vulcans can perform. The Doctor could make them appear human temporarily, although he'd have to do so in a way that would fool Devore scans.

In conclusion, we can find the other Vulcans on Voyager, if our imaginations are elastic enough.