You're thinking in the same direction as I am. I don't drip-acclimate though, I'm more of a 25%-->50%-->75% then add the fish kind of guy.
With the ammonia likely elevated, I agree that drip acclimating is probably not the safest. Matching bag parameters with tank water would be ideal. Having a bucket of low salinity water is a great idea. You could use it to quickly make a bucket with a salinity between that and your tank too if needed.
That being said, does anyone know whether the hyposalinity conditions people ship in are corrected for alkalinity? If they run at 75% the normal salinity, is the alkalinity also at 75%? Or do they boost the alkalinity and just keep the sodium chloride low? I've played around with these before, but idk what the vendors do. I'm trying to take potential pH shock into consideration.