You can. Yes. Go to your boss. Ask to be paid 60% of your current salary to work M-W. I'm sure you'll get a yes.
I'm sure he'll laugh in my face.
That means you are not making enough money.
Haha the length of time to complete projects would go through the roof, so that would never work here.
Perhaps, but that would be exactly valuing the extra free time over the pure amount of cash, which is a counterargument to your "solved by money" idea. I would take "$60,000 and a 3 day week", but "solved by money" suggests you should take "100,000 and a 5 day week".
60k for 3 days a week is exactly the same as 100k for 5 days a week.