You can probably just extrapolate. As weight goes up, enjoyment of riding goes down.

As someone who routinely overpacks, I can say that everything you carry that you do not need only decreases the enjoyment of the ride. I'm not saying don't pack a lot of stuff if you feel like you need a lot of stuff or would use a lot of stuff, but don't carry extra stuff just for the experience. The experience is: it feels bad. Well, not bad, but just worse than riding with less stuff.

Just did a long weekend trip with 70 miles of riding over two days with a rocking chair strapped to my rear rack. Not full size. Camping chair, folds up into something that's only moderately awkward and somewhat heavy. I don't regret it, because between those two days of riding there were four days of camping and sitting in that chair and listening to music. In addition to the chair, there was probably a whole other pannier-worth of gear that I only carried because it was useful during the camping portion of the trip. It made riding portion of the trip slower, harder, and less fun. Still fun, but less fun than riding with less weight. I would not throw that 5 pound chair or any of that other gear on the bike just for the experience. I'd want to know it was worth the effort of hauling it around.

I'm all for a test run with fully loaded bags to see how the bike is going to handle and how your legs are going to take it, but the advantage of credit card touring is not having to carry all that stuff.