I’ll happily fish a pva bag into (the right) silt, the carp are perfectly happy to find food there, I don’t worry too much about the bait being tainted by silt, their sensory receptors will still detect bait in silt, there’s lots of food already buried it it, so it makes sense to place a bait there. If you don’t want it crashing in too fast, then I use a lighter lead and you can use a straw to blow some air in it, tape it up around the straw, then pull it out and lick/stick shut. A few nuggets of foam and/or pop ups will increase buoyancy too. You don’t want them too buoyant as the bag if sinking too slowly may well dissolve before it hits the bottom. Not necessarily a problem in my view as it may give a slightly wider spread of free bait, but maybe not the presentation your after.