For pathfinding I think you want a long range medium ship with good stealth--either the Lancer Dur, 400i or MSR. There are no smaller ships with the needed range, nor larger ships with the needed stealth. Equipped with the competition Sparkfire, the Dur and 400i both have ranges over 900Mkm, and mostly powered down for stealth, IR sigs less than 9k. When stealth is fixed their EMs should both be below 1k. The MSR has all that plus almost twice the range of the others. Serious contender for first choice unless we find the Dur refining capability extends to quantanium. I prefer the 400i for living in, but the MSR also offers blinding top speed and in conditions like this, range is super important. (Note the best Pathfinder is not a pathfinder but a transport--another reason both the 400i and Corsair need their fuel tankage revised, and while they're at it the Kartu-Al is still waiting.)
The place to look for an abandoned Bengal is the region of space around Orion that the UEE lost to the Vanduul in battle--Virgil, Tiber, Vector, Viking, Caliban, and Vanguard. Including Orion that's seven systems to search. Given a quiet ship and some patience, there is probably a lot more to find there than just one ship, and there is a lot of fighting to do as part of the "Sons of Orion" (SOO) mission storyline.
Equipped with the same Q Drive the Vanguard and Retalliator have half that range, so may under some circumstances be able to penetrate as deeply as three jumps from Vega or Elysium, granting access to all 7 target systems. I think the Vanguard and Retalliator are going to be our primary strike platforms in the region. However, I'm convinced that to get optimal coverage of the area and use of smaller ships (Eclipse, Scorpius, Sabre, F8, Mantis) players will want to build secret bases inside Vanduul territory . This also would grant the ability to support larger ships like the Polaris. Bases supporting extended ops for hunter killers like the Polaris should be in my estimation, a goal of any military incursion into Vanduul space.
If the jumpgate map stays as was, the safest way to do this may be to use the small gate through Leir in Outsider space and jump into Vanguard (the system). That would offer a second ingress to Vanduul space that skips Virgil and Tiber, and could offer some surprise. Vulcans could then fly supplies through the Leir approach to keep a Polaris in the fight indefinitely. Eventually you'd even like to see a Crucible and Star G find their way into the region, and perhaps that is all that is needed to build a secret base. These are however, too large for the approach through Leir--they need to get through four systems to get to Viking, Caliban or Vanguard. Also note, though this is as far as UEE ships have gone and thus where we could find a Bengal to salvage, there are plenty of military reasons to explore deeper into Vanduul space. What the UEE failed to do with raw might (Idris and Javelin), TEST might do through speed and stealth using the Polaris. The main reason one wouldn't expect to see half dozen Polaris hunting as a group is the player based needed--but that's EXACTLY what TEST has in spades. A single salvo of S10 torps from 6 Polaris is about 25 million damage--likely enough to kill even a Kingship.
Salvaging anything in enemy territory is going to be a tricky operation, but I have to agree is something TEST should focus on. If we don't go get the Bengal, someone else will. Do we want to play second fiddle to another org? Of course not. There will very likely be only one salvageable Bengal in the verse and we need to be the org that owns it.
Though there was a Vanduul attack on Leir about three years ago, the system has been quiet ever since, so this may be an excellent choice to run the SOO missions with a surprising advantage. Since Leir is not protected as part of the UEE, I say "all your loot are belong to us". Great place to pick up a free Polaris. They're just waiting for us. Note on Leir though--the Vanduul attacked and destroyed an Outsider outpost there three years ago with a pair of Void Bombers, but Void Bombers are too large to fit through the gate we know about from Vanguard to Leir. So the first order of business may be to search Leir for an unknown gate entrance.
Finally, note that since the Vanduul attacked Leir with Void Bombers which cannot fit through the Leir--Vanguard gate, they do not necessarily know about that gate. If careful, an assault group could exploit this possible lack of intel to great advantage, primarily by flying Vulcan support ops through that gate to larger ships that myseriously don't need whatever gate the Vanduul have used to access that portion of Vanduul space. They, the Vanduul know about a gate we don't, and we may know about a gate they don't. Our advantage is that we know they know what we don't know, so we know we should know it, but they don't necessarily know what we know, nor even if they did we know they do not know what we know--so--we know they don't know what we know.