I think your approach is reasonably ethical. I'm not all that concerned with ethics; rather the continued funding of the websites we like. One important element of your first hypothetical is that a donation model probably won't suffice, websites will need to be able to set their price based on their costs, so it can't be evenly split between the sites you visit.
So I think the experience would be like you add $5 to your browser, then as you visit sites it asks you either to pay a one time access fee or subscribe for continued access.
But this would be the case for every site, right, because they all cost money. I wonder how many distinct websites the average user visits and if they're willing to pay that many parties that much money.
I guess my conclusion here is that bad ads should be punished by some mechanism. Unfortunately making the most targeted, helpful (and they are helpful, by the way, when done right they show you something you like) ads often incentivizes bad ad production practices like data farming and data marketplaces. I think that has to be attacked legislatively or, in your example, by direct payment.
But I think the reality of an internet gated by payments is a bigger deal than people appreciate.
(PS Not that this is usually my line of argument, but it also has the unfortunate effect of tying someone's economic status to what they can access, leading to greater isolated groups and class hierarchies in content)