How can this one ship potentially survive combat with the Borg? Alien ship with unknown capabilities.
Survive on its own without needing constant resupply? Alien ship with unknown capabilities.
Need episodes where they're trapped on the ship to save money? Unknown ship they're exploring or they trigger some function they're not sure of that created danger.
There's lots of potential there.
How can this one ship potentially survive combat with the Borg?
Simple: DON'T use the Borg. Yes, they come from the Delta Quadrant, but instead of them being around so much of it, have them be in only a small region. "UNITY" was a good one-off Borg story. Could have been the only one. (And they could still can get Seven, who was an excellent character. Maybe they could have found her like how the
Enterprise found Hugh: lone survivor of a crashed Borg ship.)
Survive on its own without needing constant resupply?
Have less UPN suit interference. If VOY was left more alone, like DS9, it would have been a better show because we would be seeing consequences on a more regular basis.
Need episodes where they're trapped on the ship to save money?
Have some day in the life episodes, or the crew paired off in a disaster-like scenario (like
"Disaster" or "STARSHIP DOWN"), or have a couple trapped in a shuttlecraft ("SHUTTLEPOD ONE").
There's lots of potential
there.