Welcome aboard ladoga2015.
Basically all plastics used in tackle are some sort of pvc plastisol, just some are less hard than others. The soft plastic we use in making the baits here are soft, but in degrees. Some are very soft and can tear easily while others can be made fairly stiff and firm and have the durability of a tire. Still, they are all considered soft plastic. The hollow bodied frogs that I have used, like a Spro frog are made from similar plastic to what we make here but "not quite" what we make here. Then too there are frogs that use the same type of plastic found in use here.
The plastics we make here can be painted as long as a cover dip is used to protect the paint coat.
The Essential series plastic which is relatively new here and to the marketplace is very, very resilient. Hardener can be added to about 10% of the volume to make it much stiffer and I do believe there are some here that can attest to the resilience or durability. Another option would be a plastic formula specific to saltwater use.