Not sure it answers your question, but for the rare times when I sit in my truck in wet clothes, I simply use Jeep towels. They are designed to be attached around the headrests so they stay in place.
Available here: Jeep Logo & Smiley Face Seat Towel
They also have them with a Mopar logo...
Definitely not seat covers, but they might be an alternate, depending on what you intend to do.