Don't worry about it. Render the treasure as per treasure parcels, and give the rest as a plot token which represents the rest of the treasure in the narrative of your game.
Dump most of the treasure parcels for the level at the end of the encounter. That means the dragon will be sleeping on about ninety thousand gold, not counting magic items. Beyond that, money in late paragon is almost entirely pointless with magic item rarity rules. Healing potions already cost as much as a small town.
What I'd recommend is, on top of focusing most of the level's treasure parcels on the hoard, say: "there's a lot more money here, I'll be giving you this level's money all in a lump, but because there's more than that, each of you get a 'plot token.' These plot tokens represent you spending massive amounts of money to affect some change onto the world. How do you want to spend them?"
By treating the hoard by treasure rules, you continue to maintain the character-required levels of wealth and other nonsense. By giving most of the hoard as "plot tokens" you explicitly acknowledge that "Hey, the characters have done something special here" and reward them by giving them a stake in the world.
By late paragon, most characters likely have pocket kingdoms (or equivalent) and are heading into the multiverse-spanning epic levels. Don't worry too much about "cash."
Example uses of plot tokens in the game that I played:
- I'd like a castle now.
- We, the group, want to found a city.
- I'm going to establish a thieves guild.
- We'll buy another airship.
The beauty of most of these requests is that they inevitably lead to more adventures. Not only that, but the plot resources implicit in these things lead to fantastic backdrops of "As your city's army battles it out with the tainted creatures of the world around the iceberg, you head inside." This investment-in-world also gave the paragon-epic characters reasons to fight without needing to deal with the standard epic quest-giver problem.
If you absolutely must give treasure qua treasure beyond the 90k in gold, gems, and art, consider a "ritualized residuum" substance. With normal residuum, casters can only create common magic items. With this stuff, say because a dragon had been using it for a bed for umpteen years, it can be used to enchant uncommon items of the players choice. You can then make the magical crystals which contain the "ritualized residuum" rather bulky, which gives an endless floor of twilit sparkly magic rocks.
Given that (the never considered size) of gold pieces in earlier editions was 1.5 to 3 times the size of one of our 50 cent pieces ninety to a hundred and fifty thousand of them is... not too bad for a floor covering. Feel free to emphasise how many there are by not counting them but providing the means for a quick fermi calculation as to their quantity.