This is under my 1990 dash. It almost looks like it would accept an SD card. The mounting seems so form fitted that it looks stock, but I do not know what it is. Are there some gurus out there who could help out?
As the Wag does have a 7-way harness and receiver, I think that you have the right idea. Now for the fun of removing more of the electrical spaghetti that the PO left me.
Given that the actual cruise control only wanted to cruise at 90mph, the wipers could not do much worse.