Let me throw in a little sand here, too.
One idea I like a lot in this sandbox is the idea of conquest and ownership. You take it, you hold it for a year, it's yours. (The implication that other adventurers can basically be treated as bandits is, well, pure bonus.) The King probably wants something back for this, though, and a money-wise King might want to see steady returns sooner rather than later. This is an idea you can put to work in other sandboxes, too, or just as a background explanation for all those dungeon bashes.
But in my experience players hate paying taxes. So what to do about that?
Here's one option.
Flat Fee - any levy or tithe is a flat fee, not a percentage. Think mobsters or tax farmers. The providing authority (in this case, King Krail) gives you the right to conquer the land and keep it . . . but you owe X amount of money per month, per year, per whatever (year is probably good) in return for this. Don't make the payment and your claim is legally forfeit. You might still be the de facto holder of the claim, but no longer de jure holder of the claim. So cough up $100,000 in gold at the end of the year and it's yours. Don't have it? Better get out and plunder a dungeon, take a loan, or chase a long-last stash of pirate gold. Or suck up hard to the king.
This works even better if the party is your usual band of murder-hobos. They don't want to settle down, but if a license to steal is $10K a year, and everything above that is profit, they're going to be extremely aggressive monster-tithing tax famers ("King says you owe everything, including your mana organs.
This one is a bit easier to swallow than taxes. If you don't want to pay the levy, fine - what you seize isn't yours. (This explains hirelings and henchmen pretty well - they want some money, but it's too big of a risk to bite off) It's a good "discuss it ahead of time" kind of thing, too - if everyone jumps in with the "we're a group of guys splitting the claim's annual levy" it even explains the remarkably commune-like approach many gaming groups take towards treasure and expendables.
This is also a good way to let one group fund a future group, if you keep the same world but different generations of gamers. Your old retired guys might loan out their magic weapons and such to new delvers, in return for a fee to be paid after they get some loot.
Just throwing this out there.