I spent 3 hours buying my last car. I got there, my friends spent time at the beach and I basically went through the entire car with the buyer.
I had him jack it up, I checked the underside, brakes, exhaust system. Then we went on a drive, first around town, we got some lunch (on me), then on the freeway for about 50 miles. I had him get on/ off a bunch and floor it. I also had him stop to get some drinks halfway through the trip.
5 hours is a bit of exaggeration but when you say "As a seller, it's a take it or leave it thing for me." I probably wouldn't want to buy anything from you. You sound like you're trying to offload damaged goods.
Also "it's going to have quirks and small issues, and any buyer should be aware of that." Well I want to know all those quirks. I hate buying a car, and going through the wiring finding it all ghetto rigged together, among other things.