So, just for a benchmark, an 8th level character has, over the course of their lifetime, earned about 100,000 gold. As gold coins, viewed in a pile, that's 100 stone. You could move at full speed if you spread that across five light horses (with a sixth for yourself.) Or you could use it to fill a third of your wagon.
Now, on one hand, most parties will not generally not hang onto 100% of their income and keep it in a pile. They'll spend a lot of it on cats. On the other hand, most parties will have more than one person, so it's conceivable that a full party might collectively have literally have a wagonload of gold.
How do you manage that? You could just have a wagon, but if worst comes to worst and you have to flee, leaving the wagon behind will ruin you. You could convert much of it into gems, but then you better pay very close attention to that sack. You could do a multi-tiered system where you keep, say, two stone of gold, and gem the rest. You could bury much of your wealth, and make a treasure map to help you remember.
In the game I ran, we didn't really worry about it. PCs were just assumed to always have full access to all their wealth, and I never had them get robbed. I'm not thinking about this from an adversarial viewpoint; I don't want to penalize PCs for not properly thinking about the precise details of physical lucre. I'm just trying to visualize the life of someone who regularly deals in more than their weight in gold.
My players like to buy jewels an jewlery as a more confortalbe and cool way to trasport wealth. A gold ring with a diamons is at avarage 10000gp, so you could carry all of your 100000gp in just 10 fingers.
Oviusly its a good idea to keep 1000gp or so for "small expenses".
That’s an interesting and hard question to answer. I think converting much of that wealth into jewelry and gems is a common answer, but I think a lot will depend on the setting.
In the current 5E campaign I’m playing in we’d placed a lot of our money in a bank run by the dwarves. It has branches in most major cities, but once we get into the boondocks we really don’t have access to our money.
In the Hellfrost campaign I’m running I converted the prices and coins to reflect a silver standard, and made the coin weights closer to some historical examples, so that 320 silver pennies weigh 1 pound. So there is some weight relief there, but I don’t think Hellfrost as a setting deals with treasure at the same higher amounts that D&D based games do. There are also letters of credit available at the temples to Var, the god of trade and merchants. They gain no interest on these letters, and in fact are charged a small fee as a percentage of the wealth deposited. To access the money you also have to visit a temple to Var, which are typically only in cities, and even then the local temple may not have the funds on hand if a major withdrawal is attempted.
I think a lot will depend on the setting. It would be interesting to know how the Auran Empire setting deals with large amounts of wealth. Is there something equivalent to a banking system? Maybe there only available in class IV markets and above? Maybe the market class also limits the withdrawal amount any given month or week?
One option that comes to mind is the a PC takes on a henchman just to handle the PC’s excess treasure as mercantile ventures, and hope it turns a profit. The money is tied up in merchandise on ships or being moved in caravans. Hope the henchman remains loyal. This might be a good place to hire a family member as a henchman (hopefully they’re more loyal than the average Joe off the street.) If the PC dies this could become the replacement PC as the henchman joins the party to avenge his sister/uncle/cousin/whatever.
Ooh, I like the idea of jewelry!
The rotund lord frowns at you for a moment, and then sighs. "Very well. You did peform... acceptably, and I'll not have it said that House Tousignaut does not pay debts." He stares at his hands for a moment and then labouriously twists off a hefty gold ring and tosses it onto the table. Small emeralds sparkle as it rolls towards you. Two more rings follow. "That should be more than acceptable."