That idea kinda falls flat if you think past what your character would do and instead think about what they would do.
Wyll will join you, but only if you promise to help him with Karlach. He's already more interested in hunting Karlach than getting rid of the tadpole anyway.
Karlach will gladly join you but if Wyll's there, they'll fight because there's no tadpole magic telling you she's not who Mizora says she is. You have no reason to spare her other than her word, and if you do, Wyll won't. If you meant that you're tadpoled but just don't know the threat, then tadpole magic could probably still happen and things transpire the same way they do now.
Astarion has no reason to join you. What use does he have for you if not to find a way to cure (or in his case, a way to control) the tadpole, if he doesn't know it's a threat? He's just happy he can walk in the sun again.
Gale might tag along assuming you're willing to help him with his personal problem.
Shadowheart may join you, since she's being hunted for the artifact and could use your protection.
Lae'zel will kill you on sight. Githyanki aren't exactly friendly. She's only reluctantly letting you be her 'servant' because she knows the depth of the tadpole issue.
And good luck ever getting Shadowheart and Lae'zel in the same party, considering what transpired before the tadpoling. They already don't want to be, and without your persuasion, will kill each other (as is in game, Shadowheart kills Lae'zel) regardless of the tadpole. Imagine how that'd go if their only concern was the artifact.
Maybe there's no tadpole magic telling Karlach isn't what Mizora says she is, but other companions (At least Shadowheart and Lae'zel) do point out that Wyll is full of shit accusing her of being a devil.
Astarion is still looking for help regarding the tadpole, though I'll admit he's the easiest to pass up on when he tries to bite you, at which point he assesses himself as a willful threat to you.
Lae'zel is still helping you, that she's doing so reluctantly is irrelevant.
You don't know the gravity of Gale's issue until you're already on better terms with him than at the start, until then you just had to feed him some magical items every now and then, and there's plenty of garbage that counts for that criteria.
Yes, Lae"zel and Shadowheart will want each other dead, but them attempting to kill one another tends to happen pretty close to Act 2, until then, it's still two people with a similar issue.
Also if you're pointing out Wyll wanting to hunt down Karlach before anything, I think there's the other issue of putting your personal problem before anything else is also bad as it throws you headfirst into the patrol and the creche at level 2 or 3, for another topic, but still, game heavily suggests you help other people - also you can tell Wyll you'll still prioritize the tadpole and he'll still tag along.
