I fitted citroen BX seats in my 90, very comfortable and cheap and even better the squab is separate so gives easy access to battery box, admit they will all be old now but you might find a good pair.
Ever since I had a non-switched short in a volvo 245 some years ago I have always fitted a quality battery isolator just in case. But there are more benefits, if I want to do some minor electrical work I can just isolate the battery and get on with it, If I am parked up in an out of the way place and away from the vehicle for a long time - as in going fishing - it gives another level of security.